A diabetes newsletter recently claimed that a herbal product called berberine, "has been shown to lower elevated blood glucose as effectively as metformin, the very popular, first-line diabetic prescription medicine. For example, in a 2008, a 3-month study with newly diagnosed type 2s, berberine significantly decreased, on average, hemoglobin A1c 21% (from 9.5 to 7.5), fasting blood glucose 35% (from 191 to 124), and postprandial blood glucose 44% (from 356 to 199). Fasting triglycerides dropped 21% (from 99 to 78)."
A herbal product that's as good as metformin in lowering BG levels? That would be awesome.
I located the quoted study on-line: Efficacy of Berberine in Patients with Type 2 Diabetes. It was a very small study, of type 2 patients taking 1500 mg of berberine per day or 1500 mg of metformin daily. There were 36 participants enrolled, and 15 completed the berberine treatment arm, while 16 completed the metformin arm. There was also a second study, of berberine plus metformin, but apparently there was no control group for this combination. No mention of blinding of either the participants nor the researchers (which is a major flaw in any study -- if either the subject or researcher knows what the patient is receiving, it's easy to warp the results). No doses other that 1500 mg total per day (divided into three doses of 500 mg) were studied, although "if heavy gastrointestinal side-effects occurred, the dose of berberine was reduced to 300 mg three times daily." In addition to the results quoted in the newsletter, gastrointestinal adverse events occurred in over a third (34.5%) of the subjects given berberine. There's also a very worrisome, very vague, statement that "None of the patients were observed with pronounced (more than 50%) elevation in liver enzymes or creatinine [a test of kidney function]." Does that mean that there were occasional patients with some elevations of liver or kidney tests? If so, I would have wanted to see what happened -- remember a drug called troglitazone (Rezulin), which frequently caused minor elevations of liver tests -- and rare dramatic elevations resulting in liver failure and death. Maybe I'm overreacting, but I sure would like to see the liver and creatinine data in more detail. Overall, an intriguing pilot study; a bigger, double-blinded study of berberine vs metformin would be interesting to see.
A scholarly review of 14 studies of berberine, including the study I discuss above, was published in 2012 (Berberine in the Treatment of Type 2 Diabetes Mellitus: A Systemic Review and Meta-Analysis). The authors of this review article concluded that "Berberine appeared to be efficacious for treating hyperglycaemia and dyslipidemia in T2DM. However, the evidence of berberine for treating T2DM should be carefully interpreted due to the low methodological quality, small sample size, limited number of trials, and unidentified risks of bias."
Should people with diabetes add berberine to their medications? It's widely available -- just Google the word to see lots of choices, in lots of different strengths. (Amazon alone has 176 listings for it)
But as is usual with unregulated supplements, it's "buyer beware" as to the quality, purity, and indeed the amount of active ingredient in these products. And as I hint at, the safety of berberine is not completely clear.
Still interested? Read Berberine Works But May Very Well Be Harmful
Finally, if you choose to use this stuff (which I'm not recommending),
a) use a product that describes the number of milligrams (combination concoctions sometimes describe that they have it, but don't necessarily tell you how much), and
b) be sure that you alert your physician that you are taking it, and
c) make sure that your physician is aware that there's some evidence that it can indeed lower blood glucose, so as he/she decides on medication adjustments, berberine's effects, both good and bad, can be taken into consideration.