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HbA1c (Glycated hemoglobin) is a biomarker of glucose metabolism, and higher HbA1c is associated with more disease progression and comorbidities in states of insulin resistance or diabetes.

Research analysis lead by Kamal Patel
All content reviewed by Examine.com Team. Published:
Last Updated:

Human Effect Matrix

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what supplements affect hba1c
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
grade-a Chromium - Very High See all 18 studies
Although sporadic evidence suggest improvements in HbA1c in diabetics, the entirety of the evidence does not support a reliable and significant improvement in diabetic persons.
grade-a Fish Oil - Moderate See all 10 studies
Although the majority of evidence suggests absolutely no influence on HbA1c, reductions have been reported and a lone case has noted a clinically irrelevant increase of HbA1c (secondary to the increase in glucose). Practically, there is unlikely to be any large changes
grade-b Berberine Strong Very High See all 3 studies
The reduction of HbA1c associated with berberine, according to a meta-analysis of diabetics using 1,000-1,500mg berberine daily, was −0.72% (95% CI −0.97 to −0.47) more than placebo. This reduction appears to be one of the more significant reductions associated with dietary supplements.
grade-b Coenzyme Q10  
grade-b Magnesium  
grade-b Psyllium  
grade-b Conjugated Linoleic Acid  
grade-b Vitamin C  
grade-c Gynostemma pentaphyllum  
grade-c Spirulina  
grade-c Alpha-Lipoic Acid  
grade-c Citrullus colocynthis  
grade-c Olive leaf extract  
grade-c Panax ginseng  
grade-c Salacia reticulata  
grade-c Arginine  
grade-c Astaxanthin  
grade-c Benfotiamine  
grade-c Cocoa Extract  
grade-c Hesperidin  
grade-c Pycnogenol  
grade-c Red Clover Extract  
grade-c Rose Hip  
grade-c Royal Jelly  
grade-c Stevia  
grade-c Vitamin D  
grade-c Vitamin E  
grade-d Ruscus aculeatus  
grade-d Aronia melanocarpa  
grade-d Moringa oleifera  
grade-d Nigella sativa  
grade-d Safflower Oil  
grade-d Tribulus terrestris  
grade-d Vanadium  
grade-d Yerba mate  
grade-d Blueberry  
grade-d Mangifera indica  
grade-d Salvia hispanica  
grade-d Sulbutiamine  
grade-d Tetradecyl Thioacetic Acid  

All comparative evidence is now gathered in our ​A-to-Z Supplement Reference.

The evidence for each separate supplement is still freely available ​here.