Skip to main content

NCCIH Clinical Digest

for health professionals

Type 2 Diabetes and Dietary Supplements: What the Science Says

November 2022

Clinical Guidelines, Scientific Literature, Info for Patients: 
Type 2 Diabetes and Dietary Supplements

diabetes diabetic
© Thinkstock

Overall, there is not enough scientific evidence to show that any dietary supplement can help manage or prevent type 2 diabetes. Some dietary supplements may provide some benefit for some conditions associated with type 2 diabetes.  It is important to note, however, that there are multiple case reports linking dietary supplement use to kidney disease, which is of particular concern because diabetes is the leading cause of chronic kidney disease and kidney failure in the United States. Supplement use should be monitored closely in patients who have or are at risk for kidney disease.

Alpha-Lipoic Acid

Αlpha-lipoic acid may be able to improve symptoms of diabetic nephropathy, however, there is not enough evidence to draw conclusions about its effect on other symptoms of diabetes. 

What Does the Research Show?

  • 2019 systematic review and meta-analysis of 12 studies concluded that alpha-lipoic acid may be able to decrease total cholesterol triglyceride and low density lipoprotein-cholesterol (LDL) levels, but did not affect levels of high density lipoprotein-cholesterol (HDL). 
  • 2021 analysis found 11 studies on combination treatment of alpha-lipoic acid and valsartan and concluded that the combination could significantly reduce the level of urinary albumin and oxidative stress, increase antioxidant capacity, and lessen renal function damage in patients with diabetic nephropathy.


  • Alpha-lipoic acid appears to be safe when used orally at an appropriate dosage. 
  • High doses of alpha-lipoic acid can cause gastrointestinal upset.
  • Alpha-lipoic acid may interact with other medications. 



Chromium may be able to provide some benefit for improving glycemic control, but the research shows conflicting results. Further, there is no clear data that demonstrate that chromium plays any role in preventing the development of diabetes. 

What Does the Research Show?

  • 2021 analysis of 24 studies found that chromium supplementation in patients with type 2 diabetes may slightly improve their lipid profiles by decreasing total cholesterol and triglyceride levels. However, the lipid-lowering properties of chromium were small and may not have clinical significance. A 2022 systematic review and meta-analysis of 10 studies found that chromium supplementation in patients with diabetes had no effect on fasting blood glucose nor blood lipid levels. However, a significant reduction in hemoglobin A1C (HbA1C) was observed. 
  • 2020 systematic review and meta-analysis of 28 studies reported that a significant reduction in fasting plasma glucose, insulin, HbA1C, and homeostatic model assessment for insulin resistance were evident in patients with diabetes after undergoing chromium supplementation. 


  • Chromium supplements may cause stomach pain, headaches, insomnia, mood changes, and bloating. 
  • There have been a few reports of serious injury such as kidney damage, muscular problems, and skin reactions following large doses.


Data from clinical trials have shown conflicting results on the effectiveness of cinnamon for diabetes. 

What Does the Research Show?

  • 2012 Cochrane systematic review of 10 randomized controlled trials involving a total of 577 participants found insufficient evidence to support the use of cinnamon for type 1 or type 2 diabetes.
  • 2020 systematic review and meta-analysis of 16 studies, along with another 2020 review and meta-analysis conducted by the same research group with 9 studies, found that cinnamon supplementation in patients with type 2 diabetes may cause a decrease in triglycerides, total cholesterol, LDL, and blood pressure compared to placebo. 
  • A 2019 analysis of 16 studies on diabetic and prediabetic patients concluded that cinnamon significantly reduced fasting blood glucose but did not impact HbA1c and lipid profiles. Another 2019 analysis of 18 studies stated similar findings. However, both reviews stated that there was high heterogeneity in the studies, and that the results should be taken with caution. 


  • Cassia cinnamon, the most common type of cinnamon sold in the United States and Canada, contains varying amounts of coumarin, a substance that may cause or worsen liver disease if large amounts are ingested. 


The increased risk of developing type 2 diabetes in people with magnesium deficiency has suggested that magnesium supplementation may provide benefits to those patients with type 2 diabetes or those at risk for developing the disease. However, results from clinical trials have not shown a clear benefit.

What Does the Research Show?

  • A 2020 systematic review of 26 studies found that magnesium supplementation reduced the fasting plasma glucose level, fasting insulin level, measures of insulin resistance, triglyceride level, and blood pressure in people with type 2 diabetes. 
  •  A 2021 systematic review and meta-analysis of seven studies involving patients with type 2 diabetes found that magnesium supplementation caused a significant reduction in LDL levels but had no significant effect on triglyceride levels, total cholesterol, or HDL levels. 
  • 2021 systematic review and meta-analysis of 25 studies concluded that oral magnesium supplementation was able to reduce fasting plasma glucose in people with diabetes. Further, in people with high risk for developing diabetes, it improved the plasma glucose levels as well as insulin sensitivity markers.  


  • Large doses of magnesium in supplement form can cause diarrhea and abdominal cramping. Very large doses—more than 5,000 mg per day—can be deadly.

Omega-3 Fatty Acids

Much research has examined the role of omega-3 fatty acids in reducing the risk of developing type 2 diabetes, but data are conflicting about the ability of omega-3 fatty acid supplementation to affect glucose levels in patients with diabetes.

What Does the Research Show?

  • 2017 American Heart Association science advisory based on 5 studies with more than 10,000 participants concluded that overall evidence from randomized controlled trials suggests no benefit of omega-3 fatty acid supplements among patients with or at risk for diabetes to prevent cardiovascular disease.
  • 2008 Cochrane systematic review of 23 randomized controlled trials involving 1,075 participants found that omega-3 supplementation in people with type 2 diabetes has no statistically significant effect on glycemic control or fasting insulin.
  • 2022 review and meta-analysis of 30 studies regarding omega-3s and diabetes found that omega-3 supplementation led to a significant reduction in fasting blood glucose and insulin resistance markers. 
  • 2020 meta-analysis of 12 studies found that fish oil supplementation for people with type 2 diabetes did not impact their glycemic control. 
  • 2019 meta-analysis and review of 83 studies concluded that omega-3 supplementation had little to no effect on plasma glucose, fasting insulin, HBA1C, and insulin resistance markers. A 2022 meta-analysis and review of 26 papers on omega-3 supplementation had the same conclusion, stating that omega-3 supplementation did not improve glycemic outcomes in patients with diabetes. 


  • Omega-3 fatty acid supplements usually do not have negative side effects. When side effects do occur, they typically consist of minor gastrointestinal symptoms.


There is some low certainty evidence that resveratrol could be effective for glycemic control in people with diabetes, but more research needs to be conducted before definitive conclusions can be drawn. 

What Does the Research Show?

  • 2020 Cochrane systematic review assessed 3 studies (total of 50 participants) on resveratrol supplementation in adults with type 2 diabetes. These studies, which were short term, showed resveratrol can reduce blood pressure, and high-dose resveratrol (more than 1,000 mg) can reduce fasting blood glucose. The studies showed neutral effects for HbA1c levels and insulin resistance, with very low certainty. 
  • In 2022, a meta-analysis on 19 studies involving a total of 1151 patients concluded that large doses of resveratrol were able to significantly reduce fasting blood glucose and blood pressure. However, resveratrol did not improve triglyceride nor HDL levels. 
  • Another 2022 meta-analysis of 17 studies concluded that resveratrol could reduce fasting blood glucose and systolic blood pressure, but the researchers noted that more research needs to be conducted to fully assess the ability of resveratrol to aid glycemic control. 


  • Resveratrol appears to be safe when used orally.
  • Resveratrol may interact with other medications, especially anticoagulant/antiplatelet drugs and supplements.


NCCIH Clinical Digest is a service of the National Center for Complementary and Integrative Health, NIH, DHHS. NCCIH Clinical Digest, a monthly e-newsletter, offers evidence-based information on complementary health approaches, including scientific literature searches, summaries of NCCIH-funded research, fact sheets for patients, and more.

The National Center for Complementary and Integrative Health is dedicated to exploring complementary health products and practices in the context of rigorous science, training complementary health researchers, and disseminating authoritative information to the public and professionals. For additional information, call NCCIH’s Clearinghouse toll-free at 1-888-644-6226, or visit the NCCIH website at NCCIH is 1 of 27 institutes and centers at the National Institutes of Health, the Federal focal point for medical research in the United States.


Content is in the public domain and may be reprinted, except if marked as copyrighted (©). Please credit the National Center for Complementary and Integrative Health as the source. All copyrighted material is the property of its respective owners and may not be reprinted without their permission.