Effect of dietary fat on diabetes-induced changes in liver microsomal fatty acid composition and glucose-6-phosphatase activity in rats

Experimental diabetes may manifest itself in a defect in liver microsomal fatty acid desaturation and increased activity of glucose‐6‐phosphatase (G‐6‐Pase). The present study was designed to determine whether these changes could be normalized by a change in the dietary fat consumed. Control and streptozotocin‐induced diabetic rats were fed nutritionally adequate diets which varied in fatty acid composition. Fatty acid analysis of liver microsomal phospholipids revealed that non‐diabetic control animals fed saturated fat (beef tallow) or a diet high in ω3 fatty acids (fish oil) exhibited a significantly higher level of 18∶2ω6 and a lower level of 20∶4ω6 in the phosphatidylcholine and phosphatidylethanolamine fractions compared with diabetic animals. Control and diabetic animals fed the high linoleic acid diet had similar levels of 18∶2ω6 in the microsomal phosphatidylcholine and phosphatidylserine fractions. Microsomal G‐6‐Pase activity was higher in diabetic than in control animals. Activity of G‐6‐Pase was lower in microsomes of control animals fed the soybean oil or the fish oil diet, but was not significantly reduced in diabetic animals fed high polyunsaturated fats. Blood glucose levels were similar in control groups fed the different diets, but the plasma hemoglobin A1c level was lower in diabetic animals fed the soybean oil diet. Cholesterol and triglyceride levels were lower in diabetic animals fed the fish oil‐based diet. The results suggest that dietary fat manipulation has the potential to change at least some of the abnormalities in the microsomal membrane in experimental diabetes.