In the following sections, we’ll outline complementary approaches that may help lower your blood sugar levels. The below strategies are not meant to replace your standard medical treatment. Make sure to consult with your doctor before making any significant changes to your day-to-day routine.
Maintaining a Healthy Weight
Being overweight or obese is the number one risk factor for high blood sugar levels, insulin resistance, and type 2 diabetes. Even a slight weight reduction can be beneficial [1, 2, 3].
The single most important thing that can help you lose weight is to consume fewer calories. Multiple studies show the effectiveness of calorie restriction in lowering blood glucose and insulin resistance [4, 5, 6, 7].
Physical activity is a great way to manage blood glucose levels, and it gets more effective with increased intensity and duration. Muscle activity burns glucose for energy and makes cells more sensitive to insulin [8, 9, 10, 11, 12].
Stress increases the levels of hormones such as cortisol and inflammatory cytokines. This results in reduced insulin production, higher insulin resistance, and increased sugar craving, ultimately leading to higher blood glucose levels [13, 14, 15, 16].
Vitamin D deficiency has been associated with insulin resistance, prediabetes, type 1 and 2 diabetes, and metabolic syndrome [17, 18, 19, 20].
Vitamin D receptors are present in the pancreas, increasing insulin secretion and sensitivity .
A moderate exposure to sunlight is the best way of increasing your blood vitamin D levels. In mice fed a high-fat diet, UV exposure (but not vitamin D supplementation) lowered weight gain, glucose intolerance, and insulin resistance .
Yoga reduced fasting and post-meal glucose levels and improved blood fat profile in multiple clinical trials on people with or at risk of type 2 diabetes, especially if combined with adequate treatment [23, 24, 25, 26].
Smoking has been clearly associated with higher glycated hemoglobin, a marker of long-term exposure to glucose that indicates poor blood glucose control and predicts risk of type 2 diabetes [27, 28].
Similarly, women with gestational diabetes who smoked at the beginning of their pregnancy showed higher glycated hemoglobin levels and blood sugar spikes after an oral glucose tolerance test .
Avoiding Air Pollution
Air pollution (particularly traffic pollution, nitrogen dioxide, tobacco smoke, and particulate matter) is a leading cause of insulin resistance and type 2 diabetes mellitus [30, 31, 32, 33, 34].
Intermediate- and long-term exposure to pollution increases fasting glucose, glycated hemoglobin, blood fat levels, and the risk of heart disease and stroke, especially in people with type 2 diabetes [35, 36, 37, 38].
Research suggests that sleep deprivation and poor sleep quality decrease the ability of cells to react to insulin, leading to increases in blood sugar levels over time [39, 40, 41, 42].
People with good oral hygiene practices tend to have lower blood glucose and glycated hemoglobin levels. Conversely, gum disease has been associated with higher levels of these markers [43, 44, 45, 46]
In a clinical trial on people with coronary artery disease, practicing meditation reduced blood glucose, glycated hemoglobin, and fasting insulin levels after 6 months .
Cutting Down on Refined Carbohydrates
The digestion of dietary carbohydrates causes a spike in blood glucose, which the body counteracts by producing insulin to stimulate its uptake into the cells. A failure to react to insulin, called insulin resistance, causes sugar to build up in the blood. Over time, this damages the pancreas and leads to type 2 diabetes .
The foods most likely to cause insulin resistance are those that greatly increase blood sugar levels (in other words, those with a high glycemic index). They include sugar-sweetened drinks, baked goods, candy, white bread, rice, and pasta, and their overconsumption is associated with type 2 diabetes [49, 50, 51, 52].
Similarly, adopting diets low in refined carbohydrates has been shown to reduce glycated hemoglobin in people with type 2 diabetes [53, 54].
As opposed to refined carbohydrates, fiber delays blood glucose spikes and reduces insulin resistance. A diet rich in fiber sources such as whole grains, legumes, vegetables, and fruit has been associated with better insulin sensitivity and a reduced incidence of type 2 diabetes in multiple studies [55, 56, 57, 58, 59, 60].
Dietary interventions replacing refined carbohydrates with fiber-rich foods significantly increased insulin sensitivity in healthy people and helped improve blood sugar control in those with type 2 diabetes [61, 62, 63, 64, 65, 66, 67].
Foods enriched in soluble fibers such as beta glucans, glucomannan, and arabinoxylan were also effective in several clinical trials [68, 69, 70, 71].
Resistant starches are starches that are resistant to digestion in the small intestine. Therefore, they don’t get absorbed (but fermented) in the gut and don’t increase blood sugar like typical non-resistant (digestible) starches do [72, 73, 74].
In several clinical trials, dietary interventions increasing the intake of resistant starch reduced sugar spikes after meals and oxidative stress, thus helping control blood sugar levels and prevent diabetic complications [75, 76, 77, 78, 79].
Dietary sources of resistant starch include coarsely-ground or whole cereal grains, seeds, legumes, starchy fruits (e.g., bananas), raw vegetables, and high-amylose starches (such as Jo’s Resistant Starch) .
A large-scale study associated high dietary intake of vitamin E with a reduced incidence of type 2 diabetes [81, 82].
Food sources of this vitamin include wheat germ, nuts, sunflower and sesame seeds, and their respective plant oils .
In several clinical trials on people with type 2 diabetes or metabolic syndrome, including vitamin E-rich sesame oil in the diet reduced blood sugar and glycated hemoglobin, as well as lowering blood pressure and improving blood fat profile. In one of them, sesame oil enhanced the effects of the antidiabetic drug glibenclamide [84, 85, 86, 87, 88].
Similarly, nuts such as pistachio, walnuts, almonds, hazelnuts, and peanuts improved blood glucose control in several trials of people with or at risk of type 2 diabetes [89, 90, 91, 92, 93].
In a meta-analysis of 7 studies on healthy people, drinking green tea was associated with an 18% lower incidence of type 2 diabetes .
Its potential to improve blood sugar control in people with type 2 diabetes or at risk of developing this condition is less clear. While it was effective at reducing fasting blood sugar in 2 meta-analyses (and fasting insulin at high doses in one of them), a third one found green tea ineffective at lowering type 2 diabetes markers in people at risk [95, 96, 97].
The differences observed may be due to the heterogeneity of the populations. A meta-analysis found green tea especially effective at lowering fasting blood sugar only in people below 55 years old or of Asian origin .
A meta-analysis associated a high intake of soy with a 77% lower risk of developing type 2 diabetes, but only in women and Asian populations. Another meta-analysis restricted the protective effects to certain soy products such as tofu, soy protein, and soy isoflavones [99, 100].
In people with type 2 diabetes, soy products (especially soy protein) modestly improved fasting blood glucose, insulin resistance, and blood fat profile [101, 102].
In a clinical trial on pregnant women with diabetes, dietary soy protein improved blood glucose, insulin resistance, blood fat profile, and antioxidant capacity .
A meta-analysis of 7 clinical trials found that including garlic in the diet lowers fasting blood glucose. In a trial on people with type 2 diabetes, supplementation with garlic tablets enhanced the effects of the antidiabetic drug metformin [104, 105].
In rats, garlic reduced blood sugar levels by decreasing the activity of the enzymes involved in the transportation of glucose in the liver .
Several clinical trials have shown that fenugreek seeds reduce blood sugar levels and improve insulin sensitivity in people with or at risk of type 2 diabetes. A meta-analysis of 10 studies confirmed the blood sugar-lowering effects of fenugreek seeds [107, 108, 109, 110, 111].
Several studies have associated adherence to a Mediterranean diet with up to 23% lower risk of type 2 diabetes among many other health benefits [112, 113, 114, 115].
In people with type 2 diabetes, this diet has been shown to help improve blood sugar control and blood fat profile [116, 117, 118].
Moderate coffee consumption has been associated with a reduced incidence of type 2 diabetes in multiple studies, especially in younger and middle-aged women. Both chlorogenic acids and caffeine seem to account for this protective effect [119, 120, 121, 122, 123, 124].
Studies show that long-term coffee consumption reduces sugar spikes and increases insulin sensitivity, leading to better blood glucose control .
Including olive oil in the diet reduces the risk of type 2 diabetes by 16%. The Mediterranean diet, which uses olive oil as its main source of fat, is recommended to improve blood sugar control [126, 127].
In a clinical trial of overweight and diabetic people, adding olive oil to their diet significantly reduced their fasting blood sugar and improved metabolic control. In another trial on older adults with diabetes, an olive oil-containing diet prevented them from losing their eyesight [128, 129].
Bilberry fruits and extracts lowered blood sugar in 3 clinical trials of people with or at risk of type 2 diabetes. Bilberries also increased insulin release and sensitivity, which is important for preventing insulin resistance. Plus, they reduced sugar and insulin spikes after meals [130, 131, 132].
Similarly, a cup of bilberry fruits or 1-2 glasses of the juice reduced sugar, insulin, and GLP-1 spikes after eating a carbohydrate-rich meal in healthy people [133, 134, 135, 136].
Blueberries improved insulin sensitivity, lowered blood glucose, and reduced inflammation and oxidative stress in several trials on both healthy people and those with or at risk of type 2 diabetes [137, 138, 139, 140, 141, 138, 142, 139].
Flavonoids in blueberries (flavonols, flavones, flavanones, flavan-3-ols, and anthocyanins) increase insulin sensitivity in the pancreas, liver, and muscles decreasing glucose concentration and the risk of type 2 diabetes [143, 144, 145].
A ketogenic diet can help lower blood sugar and improve glycemic control in type 2 diabetic patients. The low-carbohydrate diet had a more favorable outcome than a low-fat diet in people with type 2 diabetes and metabolic syndrome [146, 147, 148, 149, 150].
In a clinical trial on obese, diabetic patients, a low-carbohydrate ketogenic diet was as effective at improving blood sugar control as a low-fat diet combined with the antidiabetic drug orlistat .
Capers have been long consumed for their purported blood glucose-lowering effects in countries such as Morocco, Israel, Jordan, and Iran [152, 153, 154, 155].
In a clinical trial on people with type 2 diabetes, caper fruit extract reduced blood levels of sugar and hemoglobin bound to sugar (HbA1c) without causing any adverse effects .
In several studies in diabetic rats and mice, caper fruit extracts lowered blood sugars without changing insulin levels. Capers are believed to increase sugar breakdown and insulin sensitivity [156, 157, 158, 159].
Both bitter melon and its component polypeptide-p lowered blood sugar in old animal studies and preliminary trials on people with diabetes. Proponents claim that bitter melon has the potential to be used as a less antigenic replacement to mainstream insulin therapy in diabetics [160, 161, 162].
Most studies found bitter melon effective at lowering blood glucose (both before and after meals), improving insulin secretion, and reducing insulin resistance in people with or at risk of type 2 diabetes. However, it was ineffective in 2 trials [163, 164, 165, 166, 167, 168, 169].
When compared to antidiabetic drugs, bitter melon was as effective as rosiglitazone but less than metformin and glibenclamide. Interestingly, it was more effective than glibenclamide at preventing clogged arteries [170, 171, 172].
Cocoa polyphenols, especially from dark chocolate, improved glucose breakdown, reduced blood pressure and oxidative damage, and improved insulin resistance in a few clinical trials on healthy people [173, 174, 175].
In people with type 2 diabetes or at risk of this condition (with impaired glucose tolerance), the results of the different studies were mixed and the main benefits of cocoa polyphenols seem to be improving blood vessel function and lowering blood cholesterol rather than helping control blood sugar [176, 177, 178, 179, 180].
Low magnesium levels play a role in the development of insulin resistance, type 2 diabetes, and metabolic syndrome, while high intake of magnesium-rich foods such as whole grains, beans, nuts, and green leafy vegetables has been associated with a lower incidence of type 2 diabetes [181, 182, 183, 184].
Dietary magnesium improved insulin sensitivity and reduced fasting glucose levels in a clinical trial .
Major food sources containing magnesium are leafy green vegetables, fruits, legumes (especially soy), nuts (almonds, cashews), whole grains, red meat, and seafood [186, 187].
A study found an inverse association between storage of alpha-linolenic acid (ALA) in fat tissue and insulin resistance. Similarly, dietary ALA intake was associated with reduced insulin resistance in non-overweight people and lower risk of type 2 diabetes. In people suffering from this condition, low ALA intake increased the risk of kidney disease [188, 189, 190, 191].
Natural sources of alpha-linolenic acid include flaxseed, chia, canola, hemp, soybean, nuts, and their respective oils .
Low blood zinc levels have been associated with diabetes and prediabetes, while higher dietary intake of this mineral may protect from type 2 diabetes [193, 194, 194, 195].
Zinc ions can bind to insulin receptors and activate insulin signaling pathways. By mimicking insulin, zinc reduces the excessive secretion of this hormone by pancreatic cells and helps protect the pancreatic tissue from damage [196, 197].
Good dietary sources of zinc include red meat, seafood, dairy products, nuts, legumes, and whole grains .
Three meta-analyses revealed that ginger can reduce fasting blood glucose, insulin resistance, and HbA1c (a marker of long-term glucose levels) in people with or at risk of type 2 diabetes [199, 200, 201].
A meta-analysis of 25 clinical trials concluded that whole flaxseed (but not flaxseed oil or lignan extract) improves sugar control by reducing blood glucose and insulin levels while increasing insulin sensitivity in people with or at risk of type 2 diabetes .
Flaxseed also had beneficial effects on insulin metabolism in women with PCOS .
Multiple studies show that cinnamon reduces fasting blood glucose and insulin resistance in people with or at risk of type 2 diabetes, while its effects on glycated hemoglobin are less clear. However, the authors of most meta-analyses warned about the high heterogeneity of the different studies included [204, 205, 206, 207, 208].
Several clinical trials showed that dietary supplementation with chia seeds in healthy people reduces sugar spikes after meals by turning glucose into a slow-release sugar [209, 210, 211].
In people with type 2 diabetes, chia seeds maintained blood sugar and fat control, promoted weight loss, and helped prevent heart disease [212, 213].
A meta-analysis included lowering blood glucose after meals among the health benefits of chia seeds .
Several trials on people with type 2 diabetes or glucose intolerance found that adhering to a paleo diet (including lean meat, fruits, vegetables, and nuts, and excluding added salt, cereal grains, dairy, and legumes) for 3 months reduced blood glucose and improved insulin sensitivity [215, 216, 217, 218].
Vegetarian and vegan diets have been associated with lower blood sugar levels and reduced incidence of type 2 diabetes [219, 220, 221].
In people living with diabetes, a vegetarian diet may help lower fasting glucose levels and improve blood sugar control. However an omnivorous Mediterranean diet and the Paleo diet are more effective [222, 223].
Vitamin A is essential for the functioning of the pancreatic beta-cells, which are responsible for producing insulin. Deficiency in this vitamin leads to excessive blood glucose levels and loss of beta-cell mass. Low blood levels of the vitamin A precursor beta-carotene have been associated with insulin resistance [224, 225].
Food sources of this vitamin include dairy products, liver, fish, and fortified cereals, while carrots, broccoli, cantaloupe, and squash supply its precursor provitamin A.
Apple Cider Vinegar
Vinegar improved post-meal insulin sensitivity by 34% in insulin-resistant people and by 19% in those with type 2 diabetes. In another trial on people with type 2 diabetes, it reduced fasting blood glucose [226, 227].
In healthy people, the addition of vinegar to a high-glycemic meal significantly reduced post-meal blood sugar [228, 229].
Vinegar increased insulin-stimulated glucose uptake in cells, thus allowing insulin to do its job better and enhancing carbohydrate metabolism .
In a small trial on healthy men, intermittent fasting increased sugar uptake from the blood in response to insulin .
In people at risk of developing type 2 diabetes, intermittent fasting improved blood sugar control and insulin sensitivity [232, 233].
In those diagnosed with type 2 diabetes, the effects of intermittent fasting were mixed. Depending on the study, fasting improved glucose control, had no effects, or even increased glycated hemoglobin [234, 235, 236].
Preliminary research shows that prickly pear can lower blood sugar by up to 48% in people with type 2 diabetes, even after eating a high-carbohydrate meal [237, 238, 239].
An observational study on obese people associated higher dietary histidine with lower fasting blood glucose levels and increased insulin sensitivity .
There are a number of foods that contain high amounts of histidine and may help supplement low histidine levels. They include protein-based foods such as eggs, beef, chicken, pork, and fish. Additional histidine-rich foods include soybeans, beans, wheat, maize, quinoa, and rice .
In a clinical trial on people with type 2 diabetes, taking goji fruit carbohydrates for 3 months reduced blood glucose spikes after meals and insulin resistance .
Multiple clinical trials show that supplementation with resistant starch can reduce fasting and post-meal glucose levels while improving insulin resistance, especially in people with type 2 diabetes and obesity [243, 244, 245, 246, 247].
Supplementing the diet with resistant starch may prevent complications resulting from excess blood sugar in patients with type 2 diabetes. Resistant starch improved blood glucose levels, reduced toxins released by bacteria, increased antioxidants, and protected the blood vessels in people with this condition [248, 249].
Preliminary research in animals suggests that resistant starch may help with blood glucose by slowing down the uptake and digestion of carbohydrates, stimulating carbohydrate storage in the liver and muscles, and improving insulin sensitivity [250, 251, 252].
Aloe vera supplementation lowered blood sugar, total cholesterol, LDL (bad cholesterol) and glycated hemoglobin in people with type 2 diabetes. Similarly, it reduced blood sugar and insulin resistance in people at risk of this condition [253, 254, 255].
A meta-analysis of 9 studies found that diabetic patients had the most improvement in blood sugar after taking aloe compared to healthy patients .
In human cells, an aloe vera compound (aloe-emodin glycosides) increased glucose uptake and glycogen synthesis. This may reduce glucose levels and help stop insulin resistance .
Several meta-analyses have found that zinc supplementation may reduce blood glucose, insulin resistance, and glycated hemoglobin levels in people with obesity, diabetes (both type 1 and 2) and metabolic syndrome [258, 259, 260].
Zinc may also decrease the severity of diabetic neuropathy (nerve pain), oxidative stress, and cholesterol/triglyceride levels in type 2 diabetic patients [261, 262, 260, 263].
Supplementation with probiotics such as Lactobacillus acidophilus, L. casei, L. rhamnosus, Bifidobacterium breve, B. longum, and B. animalis improved blood glucose control in people with or at risk of type 2 diabetes in multiple trials. Moreover, they lowered blood pressure, reduced oxidative stress, and improved blood fat profile [264, 265, 266, 267, 268, 269, 270].
A meta-analysis of 11 studies found supplementation with Lactobacillus and Bifidobacterium probiotics effective at improving blood sugar control, lipid profiles, inflammation, and oxidative stress in pregnant women with gestational diabetes .
According to a review of clinical trials, chromium increases insulin function and helps prevent type 1, type 2, gestational, and steroid-induced diabetes .
Three meta-analyses concluded that chromium, both alone or in different combinations, can significantly improve blood sugar control. Chromium picolinate showed the best results [273, 274, 275].
Two meta-analyses concluded that L-carnitine supplementation can help reduce fasting glucose, insulin, and glycated hemoglobin while increasing insulin sensitivity [276, 277].
Some researchers suggest that L-carnitine may improve insulin sensitivity by affecting fat breakdown in lean tissue and muscles .
In 2 meta-analyses, spirulina significantly improved fasting blood glucose, insulin resistance, and blood fat profile in both healthy people and those suffering from type 2 diabetes and metabolic syndrome [278, 279].
However, some researchers dispute the claim that spirulina can lower blood sugar in type 2 diabetes: twelve weeks of spirulina tablets (8 g/day) didn’t change blood sugar levels in a group of diabetic Koreans. Each person’s health status (and possibly race) may affect their response to spirulina [278, 280].
A meta-analysis of 8 studies found that supplementation with stinging nettle may help reduce fasting blood sugar in people with type 2 diabetes. However, supplementation had no effect on glycated hemoglobin levels .
Chemicals in nettle leaves and stems (but not roots) appear to trigger the release of insulin and other compounds that reduce blood sugar .
In multiple clinical trials, psyllium husk consumed with meals significantly reduced both fasting and after-meal blood sugar levels, insulin spikes, and HbA1c levels. Similar results were seen in a meta-analysis of 7 studies [283, 284, 285, 286, 287, 288, 289].
In a small clinical trial, psyllium husk not only improved fasting blood sugar and HbA1c levels but also enhanced patient tolerance to the antidiabetic drug metformin .
A meta-analysis of 18 studies on healthy people found that coenzyme Q10 (CoQ10) reduced blood sugar in those with both high and normal levels with doses below 200 mg/day .
Another analysis of 14 studies on overweight and obese people with diabetes found that CoQ10 reduced blood sugar (fasting and HbA1c) and insulin levels in doses below 200 mg/day .
In 3 clinical trials of middle-aged and elderly people, supplementation with inulin significantly reduced blood sugar levels before and after meals, insulin resistance, and glycated hemoglobin [292, 293, 294].
A meta-analysis of 20 studies found that there was a tendency for reduced blood sugar levels in type 2 diabetic patients supplementing with inulin .
In 4 clinical trials on healthy people, white mulberry leaf extract reduced carbohydrate digestion and absorption, resulting in decreased blood sugar and insulin spikes after meals [296, 297, 298, 299].
The extract had similar effects in people with type 2 diabetes or at risk of developing this condition. Moreover, it helped delay the progression of diabetic kidney damage by improving antioxidant status and blood fat profile [300, 301, 302, 303].
A nutraceutical complex with white mulberry extract, red yeast rice, and berberine lowered fasting glucose, blood insulin, and hemoglobin bound to sugar (glycated hemoglobin) in 2 trials on people with high blood fat levels, possibly reducing their risk of developing type 2 diabetes [304, 305].
According to one meta-analysis, berberine may be beneficial in people with type 2 diabetes. However, the authors emphasized that the evidence was overall weak since the included trials were few and had low methodological quality. Berberine lowers fasting and post-meal glucose, and glycated hemoglobin levels according to another meta-analysis [306, 307].
Curcumin is a compound found in the spice turmeric. Multiple animal studies and preliminary clinical research have found that curcumin can lower blood sugar levels, decrease insulin resistance, improve the function of pancreatic cells, suppress the death of these cells, and ultimately prevent the development of diabetes [308, 309].
Astragalus is the most popular herb for diabetes management in China. A meta-analysis of 13 studies found both oral and intravenous astragalus effective at lowering blood glucose levels and hemoglobin A1c when added to standard treatment. However, the authors pointed to the limited quality of the included trials [310, 311, 312].
In pregnant women with gestational diabetes, Astragalus controlled blood glucose and reduced oxidative damage .
In lab animals, Astragalus improved fasting blood glucose, insulin resistance, kidney function, and insulin-producing pancreatic cell mass [314, 315, 316].
In people with type 2 diabetes, ginkgo extract improved glycemic control, psychological state, and the effectiveness of the antidiabetic drug metformin [317, 318].
Ginkgo extract can increase the activity of the pancreatic cells that produce insulin (beta cells) without causing insulin resistance [319, 320].
Moreover, ginkgo extract reduced insulin resistance, oxidative damage, inflammation, and the risk and severity of complications such as heart, kidney, and eye damage in people with type 2 diabetes and metabolic syndrome [321, 322, 323, 324, 325, 326].
Diabetes has been associated with lower L-arginine levels, disrupted metabolic pathways of this amino acid, and reduced insulin production in response to both sugar and L-arginine [327, 328].
Supplementation with L-arginine improved insulin sensitivity and increased post-meal insulin release in people with type 2 diabetes. In a long-term follow-up study of people with metabolic syndrome, supplementation with L-arginine was associated with a reduced onset of type 2 diabetes [329, 330, 331].
L-arginine may promote the formation of insulin-producing cells in the pancreas, as seen in animal studies .
A review of 16 studies determined that ginseng slightly reduced fasting blood glucose but pointed out that the different ginseng types may differ in their effectiveness, making it necessary to conduct more clinical studies [333, 334].
In healthy people, both American and Korean ginseng lowered blood glucose levels. However, a review of 2 studies determined that consistent ginseng consumption had no effect on blood sugar control in healthy individuals [335, 336, 337, 338].
In people with type 2 diabetes, Korean red ginseng also had mixed results: it lowered blood sugar, insulin resistance, and glycated hemoglobin in some studies while being ineffective in others [339, 340, 341, 342].
In several trials on healthy pregnant women, supplementation with myo-inositol prevented diabetes by 50%. The effect was strongest in overweight women, who are at highest risk. In pregnant women with PCOS, myo-inositol was more effective than metformin at preventing gestational diabetes [343, 344, 345].
In a trial of women with diabetes in pregnancy, myo-inositol reduced fasting glucose levels and insulin, beneficially impacting insulin resistance .
Myo-inositol mimics the effects of insulin and seems to enhance insulin sensitivity. Based on the studies so far, it seems better suited for overweight women .
Moringa leaf tablets taken for up to 3 months reduced both blood glucose and glycated hemoglobin (HbA1C) in people with type 2 diabetes. Similarly, high doses (4-20 g/day) of moringa leaf powder reduced blood glucose while increasing insulin production in both healthy and diabetic people [347, 348, 349, 350, 351].
Milk thistle extract (standardized to its silymarin content) reduced fasting blood sugar, insulin, insulin resistance, and glycated hemoglobin in people with type 2 diabetes. In those with type 1 diabetes and alcoholic liver damage, it also reduced oxidative stress and insulin requirement [352, 353, 354, 355].
The combination of milk thistle extract with berberine reduced the required insulin dose and lowered blood fats in people with type 1 diabetes .
Magnesium supplementation improved insulin resistance, glucose levels, blood fat profile, and blood pressure in people with or at risk of type 2 diabetes [357, 358, 359].
White Kidney Bean
In a small clinical trial, people who took 1,500 mg and 750 mg of a commercial white kidney bean extract (Phase 2) with their meal absorbed 1/3 and 2/3 of the carbohydrates, respectively. However, only a high dose (3,000 mg) was effective in another trial [360, 361].
Similarly, a blocker of the enzyme that breaks down starch (alpha-amylase) purified from white kidney beans reduced blood sugar and insulin level rises after meals in a small trial of people with type 2 diabetes .
In rats, both raw white kidney beans and their alpha-amylase blocker reduced blood sugar levels [363, 364, 365].
In one clinical study, people taking eleuthero extract had decreased blood sugar both fasting and after meals, HbA1c, triglycerides, and total cholesterol .
In diabetic mice, its active components eleutheroside E and B promoted the function of the pancreatic cells that make insulin and reduced blood glucose levels and insulin resistance [367, 368, 369].
Safflower oil (8 g/day) for 16 weeks decreased fasting blood glucose in obese, postmenopausal with type 2 diabetes .
In multiple studies on pregnant rats, safflower oil prevented gestational diabetes [371, 372, 373, 374].
In test tubes, safflower oil inhibited an enzyme that breaks down starch into simple sugars (alpha-amylases). Safflower oil may thus reduce the amount of sugars the gut absorbs from food starches, leading to fewer spikes in blood sugars after meals .
Having low L-arginine levels has been associated with diabetes and reduced insulin production in response to sugar [327, 328].
In people with obesity or metabolic syndrome, supplementation with L-arginine has been associated with a reduced onset of type 2 diabetes [376, 331].
Three clinical trials found that L-arginine supplementation can help decrease oxidative stress in type 2 diabetic patients by producing nitric oxide and activating antioxidant enzymes such as SOD. This may help prevent diabetic complications [377, 378, 379].
In 6 trials of people with type 2 diabetes, 400-1500 mg/day of propolis reduced blood sugar and boosted antioxidant defense [380, 381, 382, 383, 384].
Diabetics may develop open sores on the bottom of the foot (diabetic foot ulcers). High blood sugar levels reduce the body’s ability to heal these ulcers, causing severe infections that may even require the amputation of the affected limb. Topical propolis sped up the healing of diabetic foot ulcers in 2 small trials [385, 386].
Alpha-lipoic acid appears to have beneficial effects in the prevention of diabetes by mimicking the activity of insulin and improving glucose utilization. In some countries, it is approved as part of a treatment plan for diabetic patients [387, 388].
In several clinical trials on people with type 2 diabetes, lipoic acid decreased blood glucose and improved insulin sensitivity [389, 390, 391, 392, 393].
A Gymnema supplement (GS4) reduced the needed dose of antidiabetic medication in people with type 2 diabetes and insulin in those with type 1 diabetes. Five patients with type 2 diabetes didn’t even need any conventional treatment at all for the duration of the trial [394, 395].
In other trials on people with type 2 diabetes, both a Gymnema supplement (OSA) and ground Gymnema leaves decreased blood glucose levels [396, 397].
Gymnema extracts are believed to help improve diabetes by the combination of several actions: slowing the absorption of glucose in the gut, stimulating the release of insulin from the pancreas while helping to regenerate the cells that produce it (beta-cells, which are damaged by diabetes), and correcting the use and storage of glucose in the body [398, 399, 400].
Taking salacia tea with meals reduced blood glucose (both fasting and after meals) and glycated hemoglobin levels in a few clinical trials of people with type 2 diabetes [401, 402, 403, 404].
Oral vanadium supplements given to type 1 and type 2 diabetic patients decreased fasting blood sugar levels and insulin resistance in a few small trials. It caused no major side effects, with the exception of mild diarrhea at the beginning of the treatment period. However, prolonged use of these high doses might be unsafe [405, 406, 407, 408, 409, 410].
In clinical studies of adults and children with type 1 diabetes, adding niacinamide to insulin therapy maintained normal C-peptide levels. It preserved the function of beta cells and helped delay disease progression [411, 412, 413, 414, 415].
Niacinamide also improved C-peptide and blood sugar levels in people with type 2 diabetes .
However, oral niacinamide failed to prevent type 1 diabetes in high-risk people [417, 418].
Green cardamom reduced blood insulin and insulin resistance in some (but not all) trials of people with or at risk of type 2 diabetes [419, 420, 421, 422].
In diabetic rats, both green cardamom and the antidiabetic drug pioglitazone were similarly effective in reducing blood cholesterol and fasting blood glucose levels, and preventing liver enlargement. However, only pioglitazone effectively lowered blood glucose after a meal .
Drinking gynostemma tea for 4-12 weeks reduced blood sugar levels before meals and insulin resistance in 2 clinical trials on people with type 2 diabetes. Furthermore, gynostemma extract enhanced the sugar-lowering effect of sulfonylureas in people with this condition [424, 425, 426].
Banaba leaf may help lower blood sugar by increasing glucose tolerance. It can decrease glucose production in the body up to 30% and reduce the breakdown of storage molecules (like starch and glucagon) into glucose .
In clinical trials on people with poorly-controlled type 2 diabetes, supplementation with banaba extract lowered blood glucose without causing hypoglycemia [428, 429, 430].
In people at high risk of diabetes, a product combining banaba extract and cinnamon bark improved insulin sensitivity .
A meta-analysis of 11 small studies found that supplementation with resveratrol may improve blood glucose control and insulin sensitivity in people with type 2 diabetes, but not in healthy individuals. However, the most recent Cochrane review found the evidence insufficient to support this use of resveratrol [432, 433].
In people with metabolic syndrome, supplementation with at least 500 mg resveratrol for over 10 weeks has been shown to lower blood sugar levels .
Creatine, along with cardio training, reduced blood sugar levels in a trial of healthy but sedentary men .
Creatine also lowered blood sugar after meals with effects comparable to those of metformin and glibenclamide in people with type 2 diabetes [436, 437].
Creatine supplements greatly lowered blood sugars in several studies on animals with diabetes. However, it doesn’t seem to affect insulin sensitivity or insulin levels .
A number of clinical trials suggest that pycnogenol may lower blood glucose and glycated hemoglobin (HbA1c) if taken daily for at least 12 weeks [439, 440, 441].
However, in all the above studies, insulin levels did not change. Pycnogenol may reduce glucose levels, but it doesn’t appear to increase insulin production or insulin sensitivity.
In type 2 diabetic subjects, whey protein taken during a meal increased the insulin response and significantly decreased blood glucose levels .
Those struggling with maintaining a low sugar level in the blood can consume whey protein before a high carbohydrate meal to reduce glucose levels after the meal [443, 444].
In 2 small trials of people with type 2 diabetes, oral supplementation with lysine lowered blood glucose levels and improved insulin sensitivity [445, 446].
Similarly, lysine decreased blood glucose while increasing glucagon and insulin in healthy people .
Xanthan gum reduced fasting glucose levels and prevented blood sugar spikes after a meal without causing severe digestive symptoms in 3 clinical trials of both healthy and diabetic people [448, 449, 450].
In a trial on healthy people, inositol from carob lowered blood sugar and insulin after meals, and markers of insulin resistance. Similarly, carob fiber also kept blood sugar and insulin levels after a sugar drink in check — but only at high doses (at least 10 g) [451, 452].
In people with prediabetes, inositol from carob lowered blood sugar and insulin levels, especially in non-obese .
In people with type 2 diabetes, taking ivy gourd leaves or their extract lowered fasting and non-fasting blood glucose, as well as glycated hemoglobin [454, 455].
Drinking tea prepared from guarumo leaves reduced fasting blood glucose and glycated hemoglobin levels in 2 clinical trials on people with type 2 diabetes [456, 457].
In a clinical trial, yerba mate tea decreased fasting glucose, glycated hemoglobin, and LDL cholesterol levels in people with type 2 diabetes but had no effect on food intake. In prediabetic patients, the tea improved cholesterol and triglyceride levels and reduced their consumption of fat and cholesterol while increasing their fiber intake 
Yerba mate may have additional effects by lowering insulin resistance and reducing the formation of advanced glycation end-products. These compounds are formed from high blood sugar and contribute to diabetes complications like poor blood flow, bad vision, kidney damage, and inflammation. To obtain this last benefit, it’s best to not add sugar to the mate tea [459, 460, 461].
In 2 small clinical trials of 30 people, chanca piedra lowered their blood sugar levels. The same was confirmed in numerous studies with diabetic rats [462, 463, 464, 465, 466, 467, 468].
Chanca piedra may reduce blood sugar levels by blocking enzymes that digest complex carbs, delaying sugar absorption, and increasing sugar storage in the liver [469, 470, 464, 471].
Powdered kelp pills and polyphenols extracted from this seaweed reduced sugar levels, insulin resistance, and inflammatory markers in people with type 2 diabetes. However, kelp polyphenols were ineffective in another trial [472, 473, 474].
A study of healthy volunteers found that post-meal blood sugar levels were lower in stevia consumers than in people using table sugar or aspartame as sweeteners .
Steviol glycosides prevented blood glucose spikes in people with type 2 diabetes, but the researchers used corn starch as a control, which has a significant impact on blood sugar levels. Moreover, another clinical study failed to confirm the benefits of steviol glycosides for both type 1 and type 2 diabetes patients [476, 477].
Components of stevia such as rebaudioside A, stevioside, and steviol can increase insulin secretion by stimulating pancreatic cells and improve insulin sensitivity [478, 479, 480, 481].
In a clinical trial of people with metabolic syndrome, African mango extract reduced blood sugar and fat levels, and even caused metabolic syndrome remission in 58% of the patients. In another study of overweight volunteers, African mango seed extract decreased fasting blood glucose levels by 25% after 8 weeks [482, 483].
Moreover, its seeds may aid in diabetes management through their high content in soluble fiber .
Boswellia gum resin significantly increased blood HDL levels and decreased blood glucose, total and LDL cholesterol, triglycerides, liver damage, and glycated hemoglobin after 6-12 weeks in clinical trials of people with type 2 diabetes [485, 486].
In diabetic rats, Boswellia extract reduced blood glucose, cholesterol, and triglycerides, and prevented pancreatic cell destruction and complications in the kidneys and liver [487, 488, 489, 489].
In a clinical trial of people at risk of type 2 diabetes, supplementation with high-dose vitamin D prevented this condition by improving insulin sensitivity. Similarly, high doses of this vitamin reduced insulin resistance in pregnant women [490, 491].
People with type 2 diabetes who took collagen supplements for 3 months had lower blood sugar, blood pressure, cholesterol, and creatinine levels [492, 493].
In a clinical trial on people with type 2 diabetes, colostrum supplementation lowered blood sugar, cholesterol, ketones, and triglyceride levels. Similarly, tablets from goat colostrum reduced blood sugar and the required insulin dose in people with type 1 diabetes [494, 495].
Olive Leaf Extract
In a small trial, olive leaf extract (oleuropein) reduced blood sugar levels after meals by blocking free radical production. In another trial on overweight men, supplementation with olive leaf extract for 12 weeks improved insulin sensitivity and the activity of the pancreatic cells that produce this hormone (beta-cells) [496, 497].
In diabetic rabbits and mice, olive leaf extract lowered and restored normal blood glucose levels, improved insulin sensitivity, and reduced a marker of oxidative damage (MDA) [498, 499].
Holy Basil (Tulsi)
In a small study of people with type 2 diabetes, holy basil lowered fasting blood sugar levels by 17.6% and post-meal blood sugar levels by 7.3% .
In another preliminary clinical trial, powdered holy basil leaves (2x/day for 3 months), in combination with glibenclamide, reduced fasting blood glucose by 15.6%, postprandial blood glucose by 13.4%, and HbA1c levels by 18.2% compared to glibenclamide alone .
A water-based extract of tulsi decreased blood sugar levels in a study of diabetic rats .
Red Yeast Rice
Red yeast rice can lower cholesterol, blood pressure, and blood sugar; it also has anti-inflammatory and bone–strengthening effects. Nevertheless, doctors hesitate to prescribe red yeast for metabolic syndrome and diabetes due to citrinin toxicity and an inconsistent chemical profile [503, 504].
In a small trial, Ashwagandha decreased blood sugar levels about as effectively as diabetes medication without significant adverse side effects .
Ashwagandha also reduced blood sugar in several animal studies. In some of them, HbA1c (a measure of long-term blood sugar) and insulin levels were improved as well. Ashwagandha also protected diabtic animals from pancreatic cell damage and cataracts [506, 507, 508, 509, 510, 511].
In a pilot trial, jackfruit leaf extract taken as a tea improved blood sugar tolerance in healthy people and diabetic patients .
Treatment of healthy and diabetic rats with jackfruit leaf or stem bark extracts lowered fasting blood sugar levels, improved tolerance to sugar, and/or increased blood insulin levels. This antidiabetic activity was due to their high content in flavonoids such as quercetin [513, 514, 515, 516, 517].
In a small tria on healthy volunteers, supplementation with clove extract reduced blood glucose levels both before and after meals. The extract promoted glucose uptake by muscle cells and prevented its production in liver cells .
In a clinical trial of people with type 2 diabetes, consumption of capsules containing ground bay leaves reduced blood glucose by 21-26% after 30 days .
In a small trial of people with type 1 diabetes, a tea made from fig leaves reduced blood sugar levels after meals and insulin requirements .
Preliminary clinical research suggests that taking brewer’s yeast with chromium for 8 weeks can reduce fasting after-meal glucose levels in people with type 2 diabetes. Brewer’s yeast also reduced the need for diabetes medication such as glibenclamide .
In a trial of women with type 2 diabetes, 1 g/day of tribulus for three months reduced fasting blood sugar and glycated hemoglobin (HbA1c) .
In a clinical trial of people with type 2 diabetes, supplementation with Agaricus blazei for 12 weeks improved insulin resistance .
In a clinical trial on obese women with metabolic syndrome, histidine supplementation significantly decreased insulin resistance .
A large-scale study associated the use of glucosamine supplements with a reduced incidence of type 2 diabetes .
However, it’s important to note that glucosamine may interfere with glucose metabolism because the structure of both molecules is similar. Although it had no effects on diabetic patients with controlled sugar levels, it may raise blood glucose in people with untreated diabetes or insulin resistance [526, 527, 528, 529].
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