A combination of two compounds found in red grapes and oranges may improve the health of people with diabetes and reduce cases of obesity and heart disease, according to a new study published in the journal Diabetes.

Researcher at the University of Warwick studied two compounds found in fruits but not usually found together. The compounds are trans-resveratrol (tRES) found in red grapes, and hesperetin (HESP) found in oranges. When given jointly at pharmaceutical doses the compounds acted in tandem to decrease blood glucose, improve the action of insulin and improve the health of arteries.

The compounds act by increasing a protein called glyoxalase 1 (Glo1) in the body which neutralizes a damaging sugar-derived compound called methylglyoxal (MG). MG is a major contributor to the damaging effects of sugar. Increased MG accumulation with a high energy diet intake is a driver of insulin resistance leading to type 2 diabetes, and also damages blood vessels and impairs handling of cholesterol associated with increased risk of cardiovascular diseases. Blocking MG improved health in overweight and obese people and will likely help patients with diabetes and high risk of cardiovascular disease too. It has already been proven experimentally that blocking MG improves health impairment in obesity and type 1 and type 2 diabetes

The researchers noted an improvement in insulin resistance in trial participants produced by the compounds in eight weeks treatment that was similar to that achieved with bariatric surgery after six months. Currently, Metformin is considered for the treatment of overweight/obese people at high risk of developing type 2 diabetes. However, study results indicate the combination of the fruit compounds was found to be more effective than Metformin at reducing blood sugar in the obese and overweight trial participants.

For the study, researchers increased Glo1 expression in cell culture and then tested the formulation in a randomized, placebo-controlled crossover clinical trial involving 32 overweight and obese people, aged 18 to 80 years with a BMI of 25-40. They were given the supplement in capsule form once a day for eight weeks and asked to maintain their usual diet and their food intake was monitored via a dietary questionnaire. They also were asked not to alter their daily physical activity. Changes to their sugar levels were assessed by blood samples, artery health measured by artery wall flexibility, and other assessments by analysis of blood markers.

Researchers found the highly overweight subjects who had BMIs of more than 27.5 with treatment displayed increased Glo1 activity, decreased glucose levels, improved working of insulin, improved artery function and decreased blood vessel inflammation. There was no effect of placebo.

Although the same compounds are found naturally in some fruits, the amounts and type required for health improvement cannot be obtained from increased fruit consumption. The compounds that increase Glo1 and are called a ‘Glo1 inducer’. Pharmaceutical doses for patients with obesity, diabetes and high risk of heart disease could be given to patients in capsule form.