Intake of a diet high in trans monounsaturated fatty acids or saturated fatty acids. Effects on postprandial insulinemia and glycemia in obese patients with NIDDM.

OBJECTIVE: High intake of trans fatty acids and saturated fatty acids (SFAs) is known to increase the risk of coronary heart disease. We studied the effects of diets enriched in various fatty acids on postprandial insulinemia and fasting serum levels of lipids and lipoproteins in obese patients with NIDDM. RESEARCH DESIGN AND METHODS: Sixteen obese NIDDM patients were studied in a free-living outpatient regimen. After a run-in period, the patients received three different isocaloric diets for 6 weeks using a randomized crossover design. The patients were instructed to keep the energy intake from carbohydrate and protein constant at 50 and 20 E% (percent of energy intake), respectively, on all three diets. The fat composition of the diets differed: saturated fat (SAT) diet (20 E% SFAs, 5 E% polyunsaturated fatty acids [PUFAs], and 5 E% monounsaturated fatty acids [MUFAs]) versus cis monounsaturated fatty acid (CMUFA) diet (20 E% cis-MUFAs, 5 E% PUFAs, and 5 E% SFAs) versus trans monounsaturated fatty acid (TMUFA) diet (20 E% trans-MUFAs, 5 E% PUFAs, and 5 E% SFAs). Fasting serum levels of lipids and lipoproteins were measured at baseline and in the fasting state before meal tolerance tests at the end of each study period. Insulin secretion was assessed from incremental serum insulin and C-peptide responses during the meal tests. RESULTS: BMI, waist-to-hip ratio, and glycemic control remained stable throughout the study. After meal stimulation, postprandial glycemic responses were similar on all diets; however, serum insulin and C-peptide responses were greater following the TMUFA and SAT diets than following the baseline or CMUFA diets (P < 0.05). No statistical difference was found in fasting levels of serum lipids (total cholesterol, triglyceride, phospholipid, and nonesterified fatty acids) or lipoproteins of HDL cholesterol, VLDL cholesterol, LDL cholesterol, and apolipoprotein B between diets. CONCLUSIONS: In the presence of unchanged glycemia, both dietary trans fatty acids and SFAs induce an increase in postprandial insulinemia in obese patients with NIDDM.

[Dietary treatment of diabetes mellitus. Background and rationale for recommendations in the 1990's]. / Diaetbehandling ved diabetes mellitus. Baggrund og rationale for rekommandationer i 1990'erne.

Individual dietary regulation is still an important part of all forms of treatment of diabetes. In insulin dependent diabetes (IDDM) it is rational to advise the patient 1) to arrange his diet so that this results in a low glycaemic response, which implies a relatively high intake of dietary fibre and polysaccharides, 2) to distribute the food into 5-6 daily meals and 3) to consume a low-fat diet. This prevents too pronounced postprandial hyperglycaemia and hypoglycaemia between meals. Simultaneously, insulin sensitivity is increased and not only the insulin requirement but also peripheral hyperinsulinism tend to be reduced. Dietary regulation in IDDM is thus a compensation for the defective synchronization of variations in the plasma levels of glucose and insulin in the present day forms of insulin therapy. Nine out of ten diabetic patients are non-insulin dependent (NIDDM). The great majority are obese, 50% have essential hypertension and just as many have dyslipidaemia (raised serum triglyceride and reduced serum high density lipoprotein (HDL)-cholesterol). The condition is characterized pathophysiologically by insulin resistance in muscle, fat and liver tissue and delayed and frequently reduced glucose-stimulated secretion of insulin. The most important element in dietary regulation in NIDDM is, therefore, reduction of the energy content of the food with the object of achieving and maintaining reduction in weight. Even moderate reduction, in the majority of NIDDM patients, will have the effect that metabolism of carbohydrates and lipids becomes approximately normal on account of considerable increase in insulin sensitivity and to a lesser degree increased secretion of insulin.(ABSTRACT TRUNCATED AT 250 WORDS)

High-carbohydrate, low-fat diet: effect on lipid and carbohydrate metabolism, GIP and insulin secretion in diabetics.

The effects of increasing the dietary polysaccharide content from the customary 40 percent to 50 percent of total energy intake were examined in a metabolic ward-cross-over study of eight noninsulin dependent diabetic patients with normal fasting C-peptide concentration. The aim was to study the effect of a raised carbohydrate content; therefore, the fibre content of the diet was kept approximately constant. Patients had been treated with diet alone, and the high carbohydrate (HC) observation period lasted for two weeks. Blood glucose was significantly increased postprandially in the HC period (11.8 +/- 0.3 versus 10.7 +/- 0.4 mmol/l), and this was accompanied by significantly raised immunoreactive insulin (IRI) concentrations. The secretion of IRI, C-peptide and gastric inhibitory polypeptide (GIP) after a standard meal-challenge at the end of each period were unaffected by the preceding diets. The HC diet was accompanied by increasing values of plasma triglyceride (1.13 +/- 0.06 versus 0.97 +/- 0.06 mmol/l) and VLDL-triglyceride (0.69 +/- 0.04 versus 0.50 +/- 0.04 mmol/l), whereas the ketone body concentration was decreased (0.25 +/- 0.03 versus 0.36 +/- 0.05 mmol/l). Both HDL- and LDL cholesterol were decreased by the HC-diet (1.07 +/- 0.02 versus 1.18 +/- 0.02; 3.45 +/- 0.09 versus 3.89 +/- 0.09 mmol/l, respectively), while the LDL to HDL cholesterol concentration ratio remained unaffected. Thus, in two weeks, a HC diet resulted in hyperglycaemia, hyperinsulinaemia, hypertriglyceridemia and a state of antiketogenesis, without any apparent change in the capacity of mealinduced insulin release. LDL- and HDL-cholesterol were lowered to the same extent.(ABSTRACT TRUNCATED AT 250 WORDS)