Effects of a high-monounsaturated fat diet on glucose and lipid metabolisms in normal and diabetic mice

The beneficial effects of high-monounsaturated fat (high-MUFA) diets on diabetic patients have been reported, whereas studies concerning the effects on animals have been few. Although experiments on animals should be useful in elucidating underlying mechanisms, it is not clear even whether there are benefits of a high-MUFA diet in animals. This study examined the short-term effects of a high-MUFA diet on normal and genetically diabetic mice. The high-MUFA diet supplied 38% of the total calories as fat (26%, from MUFA), while a regular diet was 13% fat (3% from MUFA). Normal C57BL/6J and diabetic C57BL/KsJ-db/db mice were fed either the regular or the high-MUFA diet for I wk. Serum glucose and lipid levels were then measured. In normal mice, hepatic triglyceride production was also compared between the two dietary groups using the Triton WR1339 method. An oral glucose tolerance test was conducted on the diabetic mice. After I wk of feeding to normal mice, the high-MUFA diet was seen to lower serum triglyceride levels and reduce hepatic triglyceride production in comparison with the regular diet; it is suggested that the lowering of triglyceride consists of mechanisms including reduced hepatic triglyceride production. When diabetic mice were fed the high-MUFA diet with a controlled caloric intake, the serum glucose levels lowered without an accompanying deterioration in lipid metabolism and the impaired glucose tolerance was ameliorated. This study demonstrates that a high-MUFA diet can lower serum triglyceride levels in normal mice and improve disorders of glucose metabolism in diabetic mice.