Dietary fat composition can influence membrane composition in a variety of cell types. Changes in dietary fat can alter the structure and function of lymphocyte membranes, liver plasma membranes, brain synaptosomes and cardiac mitochondria. In diabetics, uptake of glucose is enhanced due to a greater passive permeability of the intestine to glucose. This enhanced absorption from the intestine can be partially corrected by insulin administration and islet cell transplantation. In clinical practice, however, a more commonly used therapeutic modality for diabetics is diet modification. In this study, when diabetic rats were fed a high fat diet, high or low saturated to polyunsaturated fatty acid, there was an improvement in the plasma and urine glucose. This improved clinical response was also observed in the glycosylated hemoglobin response in the animals fed the high polyunsaturated to saturated fatty acid diet. The clinical improvement observed after feeding with these diets, however, was not seen during the oral and intravenous glucose tolerance tests. This study shows that dietary alteration can improve the clinical response in diabetic animals.