The prevalence of diabetes in India is increasing at an alarming rate as lifestyle and eating habits change rapidly. There is renewed interest in the use of traditional herbs to help manage blood sugar levels. Coccinia (Coccinia cordifolia syn. C. indica, Cucurbitaceae) is an herb that has been used widely since ancient times in traditional Ayurvedic medicine (where it is known as tindora or tindori) in the treatment of diabetes-like conditions. Aqueous alcoholic extracts of coccinia leaves and fruit have been shown to reduce blood sugar levels in diabetic animals, but few clinical trials have been conducted in humans. The purpose of this trial was to evaluate the effects of a similar coccinia extract on blood glucose levels in people newly diagnosed with diabetes.

This randomized, double-blind, placebo-controlled trial was conducted at St. John’s Medical College Hospital in Bangalore, India. The subjects were adults recently diagnosed with type 2 diabetes who would normally be treated with dietary and lifestyle modifications only. They were randomly assigned to receive capsules containing coccinia extract or placebo. The coccinia extract was prepared by extracting the leaves and fruit with 50% alcohol, purifying by fractionation, and spray-drying the filtered liquid. Fifteen kg of the herb provided 1 kg of the final extract. (Both coccina and placebo capsules were prepared by Green Chem, Bangalore, India.) Subjects took 2 capsules daily, providing a total of 1 g coccinia extract or 1 g maltodextrin placebo, for 90 days. This amount was chosen as equivalent to the traditional Ayurvedic dose of approximately 15 grams of dried herb (“a handful”) daily.

All subjects were prescribed regular exercise and a low fat, high-fiber diet to control their blood sugar. The subjects underwent a physical examination, laboratory testing, and assessment of dietary and exercise habits on days 0, 45, and 90 of the study. They returned to the clinic every week to be weighed, report any adverse effects, obtain the week’s supply of study capsules, and rate their compliance with the dietary advice, the physical activity recommendations, and the study capsules.

Sixty subjects ranging in age from 35 to 60 years were enrolled in the study, and 59 subjects completed the study. At the end of the trial, the coccinia group had a significant decrease in fasting blood glucose (P < 0.05), with a mean reduction of 15.6% (20.6 mg/dl) compared to baseline. The placebo group had a non-significant increase in fasting blood glucose of 6% (8 mg/dl). The coccinia group also had a significant (P < 0.05) decrease in postprandial (2 hours after breakfast) blood glucose levels of 18.5% (34 mg/ dl), while the placebo group had a non-significant increase of 7% (12 mg/dl) after breakfast. Glycosylated hemoglobin, a measure of long-term glucose control, dropped significantly (P < 0.05) in the coccinia group after 90 days but remained unchanged in the placebo group. The low density lipoprotein (LDL) cholesterol in the coccinia groups was also reduced significantly (P < 0.05) by 14.6% after 90 days compared to the baseline value.

No significant differences were found between the two groups for weight loss, percent body fat, body mass index, waist and hip circumferences, blood values, daily calorie intake, or compliance with diet and physical activity recommendations. No serious adverse events were reported. More than half of subjects (59%) in the coccinia group reported mild hypoglycemic symptoms such as sweating, excessive hunger, and slight dizziness once or twice during the study, usually during mid-morning, that were controlled by a snack at that time. Other minor complaints were similar for the 2 groups of subjects.

These results suggest that coccinia has a hypoglycemic action that is independent of food intake or weight loss. The authors conclude that coccinia may represent a beneficial adjunct for the treatment of people with mild type 2 diabetes. The mechanism of action of the herb is not well understood, but it appears to mimic the effects of insulin. Insulin levels were not measured in this study, so it is not known if coccinia enhances insulin production or function. Future trials of coccinia should measure insulin concentrations, include larger numbers of subjects with varying degrees of disease severity, assess dosage variations, and evaluate the mechanisms of action to determine if its effects are applicable to patients with type 1 diabetes.

—Heather S. Oliff, PhD