The National Coffee Association (NCA) in the US reports that coffee and caffeine appear to reduce pre-diabetic conditions induced by a high-fat diet, according to a new Japanese study.
Scientists at Nagoya University found that coffee and caffeine improved insulin sensitivity and glucose tolerance in rats whose glucose tolerance had been impaired by diet. The findings enhanced prior evidence that coffee/caffeine helps regulate hyperglycemia, or high blood sugar, in spontaneously diabetic animals.
In the study, rats fed a high-fat diet were split into two groups, one given plain drinking water (the control group) and the other a diluted coffee or caffeine solution. The second group showed improved glucose tolerance, insulin sensitivity and hyperinsulinemia, or high insulin levels, when compared with the control group.
The liver levels of inflammatory cells and genes related to fatty acid synthesis were lower in the coffee and caffeine groups than in the control group. This finding is consistent with reduced insulin sensitivity, as observed, leading to an improvement in glucose tolerance.
Researcher Yuji Matsuda and team also commented on the potential effects of coffee versus caffeine. Since coffee and caffeine were found to be equally effective for offsetting high-fat-diet induced impaired glucose tolerance, they reasoned, caffeine is suggested to be one of the most effective anti-diabetic compounds in coffee.
Continuing their analysis, they pointed out that previous studies had found that consumption of decaffeinated coffee was also correlated with a reduction in diabetes incidence. They noted, too, that prior research showed that decaf might improve the insulin sensitivity of the skeletal muscles and that coffee components other than caffeine showed a beneficial effect on glucose metabolism.
These results led the team to speculate that there are anti-diabetic compounds in coffee other than caffeine and to comment that they are searching for those unidentified compounds. Moreover, the researchers reasoned that since high-fat-induced type 2 diabetes occurs frequently in humans, their findings suggest that coffee consumption would be effective as a preventive measure against human type 2 diabetes.
