Can turmeric improve blood glucose levels?

This study investigated whether turmeric, or compounds present in turmeric, could lower blood glucose levels in people with abnormal blood glucose levels. It was determined that compounds related to turmeric could reduce fasting blood glucose (FBG, blood glucose after a period without food or drink) concentrations and reduce HbA1c levels (average blood glucose over last 3 months).

Dysglycemia is abnormal blood glucose levels that are seen in people with pre-diabetes, diabetes, and other conditions. It is believed that the main components of turmeric, the curcuminoids (such as curcumin) have health benefits. Whether they can affect glucose levels in people with dysglycemia is uncertain.

This study examined data from 11 studies. 1144 adults with prediabetes, type 2 diabetes, or without diabetes participated in these studies for at least 4 weeks. 570 participants received turmeric extract, curcuminoid mixtures, or curcumin (experimental group). 574 received a placebo (drug with no active effect).

Overall, FBG concentrations decreased an average of 8.88 mg/dL more in the experimental group than in the placebo group. People with higher FBG concentrations at the start of the study experienced the greatest reduction in FBG. In patients with prediabetes or type 2 diabetes, the FBG decreased by 13.86 compared to placebo. In non-diabetic people, no significant difference between experimental and placebo groups were seen. Participants who received curcumin or curcuminoid mixtures had a significant reduction in FBG. Those who received turmeric extract did not.

Overall, HbA1c levels fell an average of 0.54% more in the experimental group than in the placebo group. Those who received curcumin experienced a greater reduction than the placebo group. However, those who received curcuminoid mixtures did not. None of the studies examining HbA1c levels used turmeric extract.

Neither turmeric, curcumin, nor curcuminoid mixtures were able to improve beta cell function. Beta cells produce insulin, which lowers blood glucose. 

The study concluded that curcumin and curcuminoid mixtures were able to reduce FBG concentrations in people with dysglycemia. They also concluded that curcumin could decrease HbA1c levels in these patients. 

There were large differences between the studies (such as doses given) that may have made comparisons difficult. Furthermore, how curcumin and curcuminoids may decrease FBG concentrations is still unclear.

Discuss the use of curcumin, circuminoids, and other herbal remedies, in addition to regular treatment, with your physician.