Red ginseng lowers postprandial blood sugar levels in diabetic patients – but is this good or bad news?

‘Red ginseng’ is an herbal medicine prepared by steaming raw ginseng. This process is believed to increase its pharmacological activity. Further conversion through fermentation is thought to increase its intestinal absorption and bioactivity to diminish its toxicity.

Red ginseng (RG) is traditionally used for diabetes. Our own systematic review of 4 RCTs concluded that the evidence for the effectiveness of RG in controlling glucose in type 2 diabetes is not convincing. Few included studies with various treatment regimens prohibit definitive conclusions. More rigorous studies are needed to clarify the effects of RG on this condition.

Now a new RCT has become available. This study was conducted to investigate the effects of daily supplementation with fermented red ginseng (FRG) on blood sugar levels in subjects with impaired fasting glucose or type 2 diabetes. It was a four-week long, randomized, double-blind, placebo-controlled trial. Forty-two subjects with impaired fasting glucose or type 2 diabetes were randomly allocated to two groups assigned to consume either placebo or FRG three times per day for 4 weeks. Fasting and postprandial glucose profiles during meal tolerance tests were assessed before and after the intervention.

Compared to the placebo, FRG supplementation led to a significant reduction in postprandial glucose levels and to an increase in postprandial insulin levels. There also was a significant improvement in the area under the curve (AUC) in the FRG group. However, fasting glucose, insulin, and lipid profiles did not differ from the placebo group.

The authors of this trial concluded that daily supplementation with FRG lowered postprandial glucose levels in subjects with impaired fasting glucose or type 2 diabetes.

What should we make of these findings? Do they indicate that FRG might be an alternative to conventional anti-diabetic drugs? I would caution that we have tons of data for the latter, while we know far too little about FRG to recommend it for routine use.

On the contrary, the findings could suggest that diabetic patients who are well-controlled with diet or anti-diabetic medication should be avoiding ginseng products. If they actually work, they might significantly interfere with their metabolic control which, in turn, could even endanger their lives.