OBJECTIVE To compare the effects of a nigh-carbohydrate diet on blood glucose and plasma lipids in NIDDM patients with either mild or severe glucose intolerance.

RESEARCH DESIGN AND METHODS A crossover design with a 15-day intervention diet was used. Eighteen patients were separated into two groups on the basis of hypoglycemic treatment (diet, n = 9, or diet plus glibenclamide, n = 9) and were assigned to a 15-day treatment with a high-carbohydrate/low-fiber diet containing 60% energy from carbohydrate and 20% from fat or a low-carbohydrate/low-fiber diet with 40% energy from carbohydrate and 40% from fat and then crossed over to the other diet for 15 more days.

RESULTS The high-carbohydrate diet produced a significant increase in postprandial blood glucose in patients on glibenclamide (13.6 ± 1.4 vs. 11.0 ± 1.8 mmol/l, P < 0.002, while no difference was recorded in the group on diet alone (9.7 ± vs. 8.9 ± 0.6 mmol/l). Postprandial insulin levels were significantly higher after the high-carbohydrate diet in the group on diet along (248 ± 32 vs. 192 ± 28 pmol/l, P < 0.01), while no significant differences were observed in the other group (226 ± 19 vs. 202 ± 24 pmol/l) The high-carbohydrate diet also induced a significant increase in fasting plasma triglyceride concentrations in both groups (1.36 ± 0.2 vs. 1.12 ± 0.2 mmol/l, P < 0.05 and 1.4 ± 0.3 vs. 1.1 ± 0.1 mmol/l, P < 0.05). No differences were observed in fasting plasma cholesterol and HDL.

CONCLUSIONS The effects of the high-carbohydrate diet on blood glucose control in NIDDM patients differ according to severity of glucose intolerance.