"To our knowledge, we provide the first evidence that EGCG consumed in the diet exerts potent antidiabetic activity in vivo in a dose-dependent manner," wrote lead author Swen Wolfram of DSM in the Journal of Nutrition.
The study looked at 37 male mice who were severely diabetic, and divided them into four groups. The rats were fed 2.5, 5 or 10 grams of EGCG per kilogram of diet, or a placebo, for seven weeks.
At the five-week mark, the researchers tested oral glucose tolerance and found that glucose levels reduced by 23, 35 and 48 percent in the 2.5-, 5- and 10-gram categories respectively. At six weeks into the study, the scientists tested insulin tolerance and blood samples were taken at the end of the test to analyze glucose, free fatty acids and triacylglyceride levels. All improved on a dose-dependent basis.
The researchers also studied the effects of 5 grams of EGCG per kilogram of diet over a 10-week period on mildly diabetic rats and found that glucose tolerance, blood glucose levels, and free fatty acid plasma concentrations all improved. Analysis of rat liver cells revealed that EGCG down-regulated the genes involved in gluconeogenesis and the synthesis of fatty acids, triacylglycerol and cholesterol.
"Our data suggest that supplementation with EGCG could potentially improve glucose tolerance in humans with type-2 diabetes mellitus," concluded the researchers. "This hypothesis should now be investigated in randomized placebo-controlled trials." Wolfram said that DSM intends to begin such trials soon.
In the United States, more than 20 million people suffer from diabetes -- about 7 percent of the population -- and about 19 million people in the European Union are so afflicted -- about 4 percent of the population. The cost of treating the disease is about $132 billion, according to the American Diabetes Association.