The cornerstones of diabetes prevention are healthy diet and maintenance of desirable weight. The most focus of diet has been the role of caloric restriction to improve glycemia in overweight and obese individuals. The Kuopio Ischemic Heart Disease Risk Factor Study (KIHD) provides an opportunity to evaluate the potential role of diet and new onset diabetes in Finnish men.

The observational data from KIHD included measurement of omega-3 polyunsaturated fatty acids (PUFAs) by dietary history. Long-chain omega-3 PUFA levels are considered to be a reliable indicator of the level of fish consumption in the diet.

Over an interval of almost 20 years, there was a linear inverse relationship between omega-3 PUFAs and incident type 2 diabetes. Men in the highest quartile of omega-3 PUFA enjoyed a 33% lesser likelihood of incident diabetes, adjusted for other risk factors. The mechanisms by which omega-3 PUFAs exert a protective effect on incident diabetes are not fully understood, especially since studies that examine fish (or fish oil supplements) have not detected any direct impact on glucose metabolism. On the other hand, because higher fish intake is associated with lesser adiposity, avoiding the diabetogenic effects of obesity may be an important contributor.