Determination of membrane lipid differences in insulin resistant diabetes mellitus type 2 in whites and blacks.

OBJECTIVES: Insulin resistance in diabetes mellitus type 2 (DM2) can result from membrane lipid alterations. Blacks are at a higher risk of developing DM2; therefore, we investigated whether membrane lipid differences exist between blacks and whites and if differences contribute to impaired insulin binding in diabetes. METHODS: Subjects were recruited from four groups: white control (n = 10), black control (n = 10), white diabetic (n = 5), and black diabetic (n = 10). Diabetic subjects who had DM2 with insulin resistance on insulin monotherapy were matched by age and sex. The following determinations were made: fasting serum glucose, fasting serum insulin, plasma lipid profile, red blood cell (RBC) membrane lipids and cholesterol, and RBC insulin binding. RESULTS: The membrane lipid analysis showed racial differences in phosphatidyl ethanolamine (PE) and phosphatidyl choline (PC). The plasma membrane of whites showed higher PE and lower PC levels than that in blacks. The RBC rheologic (PE/phosphatidyl serine) properties (deformability) were lower in diabetics and black subjects. The saturated nature of RBC ([sphingomyelin + PC)/(PE + phosphatidyl serine]) was the lowest in white control subjects (P < 0.056). CONCLUSION: The combination of increased saturated/polyunsaturated fatty acids, increased saturated nature, and increased cholesterol/phospholipid can contribute to decreased membrane fluidity, resulting in insulin resistance. Also, decreased RBC deformability can make oxygen delivery through the capillaries difficult, create tissue hypoxia, and contribute to some of the known complications of diabetes. Membrane lipid alteration may be one of the reasons for a higher incidence of diabetes among blacks.

Muscadine grape products intake, diet and blood constituents of non-diabetic and type 2 diabetic subjects.

OBJECTIVE: Red wines and grape juices contain polyphenolics with antioxidant and antiplatelet properties that may be protective against oxidative stress leading to hypertension, insulin resistance, and type 2 diabetes (T2D). This study evaluated the effects of supplementing meals of subjects with 150 mL of muscadine grape juice (MJ), muscadine grape wine (MW), and dealcoholized muscadine grape wine (Dz-W) on glycemic indices, blood constituents, lipid profile, anthropometric, and nutrient intakes of healthy and T2D subjects over a 28-d period. METHODS: Subjects with T2D were assigned to take MJ, MW, or Dz-W. Non-diabetics consumed MJ and controls were given no test drinks. Several metabolic indicators associated with diabetic conditions were measured at baseline and repeated after 28 d. RESULTS: Diabetics given MW and Dz-W showed lower levels of blood glucose, insulin, and glycated hemoglobin, indicating better glycemic control. Elevated dietary vitamin C and E levels were observed in diabetics given Dz-W, indicating improved antioxidant status. Decreased red blood cell membrane saturated fatty acids and increased mono- and polyunsaturated fatty acids for subjects with T2D given MW suggested improved membrane fluidity. Lower sodium and chloride values for subjects T2D given MW suggested lower risk for developing hypertension. Improved hepatic conditions were noted by decreases in alanine aminotransferase and aspartate aminotransferase among subjects with T2D given MW, indicating better insulin sensitivity and decreased tendency toward impaired liver function. CONCLUSION: Daily intake of 150 mL of MW or Dz-W with meals improved several metabolic responses among diabetics compared with diabetics given MJ.

Differences in the metabolic response to exogenous homocysteine in juvenile and adult rabbits.

Homocysteine has recently received a lot of attention as an independent risk factor for atherosclerotic and thrombotic cardiovascular disease. Plasma homocysteine levels tend to rise with age, but are also greatly influenced by nutritional factors. Early reports suggested that there were differences in the metabolism of homocysteine in adult and immature animals. The current work tests the hypothesis that adult and juvenile animals respond differently to chronic administration of homocysteine. We have previously found that adult rabbits given homocysteine parenterally twice daily for seven weeks developed progressive folate deficiency and concurrently developed an impairment of homocysteine metabolism. We now report that juvenile rabbits do not develop folate deficiency with chronic homocysteine loading and do not have progressively higher trough levels of homocysteine, as do the adults. In addition, juvenile rabbits that have been chronically pre-treated with homocysteine exhibit a lower peak homocysteine level after a single dose than do juvenile rabbits that have never received homocysteine. This adaptation did not occur in the adult rabbits. In addition, adult homocysteine-treated rabbits had evidence of oxidative stress as evidenced by higher levels of malondialdehyde in liver tissue than adult controls. The homocysteine-treated juvenile rabbits had the same levels of malondialdehyde as the juvenile control rabbits. We conclude that the plasma elimination kinetics are altered in juvenile rabbits in response to homocysteine pre-treatment. The difference in metabolism of homocysteine may protect the juvenile rabbits from the damaging effects of homocysteine. Future studies are planned to elucidate the mechanism of this adaptive response.

Fatty acids, diet, and body indices of type II diabetic American whites and blacks and Ghanaians.

OBJECTIVE: This research was designed to study the diet, lipid profile, and metabolic and body indices of type II diabetic and non-diabetic subjects among American white and black and Ghanaian populations. METHODS: Fifty-one type II diabetic and non-diabetic volunteers were recruited through medical clinics. Data collected included food intake and anthropometric measurement. Blood samples were taken for glucose and serum lipid analyses. Serum non-esterified fatty acids, very low-density lipoproteins, low-density lipoproteins, high-density lipoproteins, total cholesterol, and triacylglycerols levels were measured. RESULTS: The Ghanaian subjects had lower body mass indexes than did the American white and black subjects (P < 0.01), although they recorded the highest carbohydrate intake. Dietary fat intake was not significantly correlated with body fat level or body mass index among the different observational groups. The serum ratio of saturated to polyunsaturated fat was higher in all diabetics than in controls and higher in Ghanaians than in Americans. Total cholesterol, triacylglycerols, and lipoproteins were within normal ranges for diabetic and non-diabetic subjects. The ratio of total cholesterol to high-density lipoprotein cholesterol was slightly elevated among the white diabetics (P < 0.05). CONCLUSIONS: The data showed a higher metabolism of carbohydrate for energy in the Ghanaian group than in the other groups. In addition, fat metabolism may differ between Americans and Ghanaians. For many variables, black Americans were more similar to white Americans than to Ghanaians. These observations imply that cultural factors may contribute more than ethnic origin to the etiology of diabetes.