Long-term comparison of three dietary prescriptions in the treatment of NIDDM

To compare three sets of dietary guidelines for the treatment of non-insulin-dependent diabetes (NIDDM) in free-living individuals and to observe the effects on metabolic control over an 18-month period.

Seventy volunteer subjects with NIDDM were randomly assigned to one of three diets, a weight-management diet, a high-carbohydrate/fiber diet, or a modified-lipid diet and followed for 18 months. Nutrient intakes, weight, blood lipids, and glycemic control were measured.

In all diet groups, glycated hemoglobin (HbA1) fell significantly before diet intervention began, remaining lower throughout the study and at follow-up 9 months later. Low-density lipoprotein (LDL) cholesterol showed a sustained fall in all groups after diet intervention. Apart from transient changes in high-density lipoprotein (HDL) cholesterol and triglyceride (TG) in the diet groups with the higher carbohydrate intake, no lasting differences were found between the three diet groups.

In the long term, there were few differences in the outcome of the three dietary prescriptions. Even with intensive instruction, participants found it difficult to meet recommended nutrient intakes; however, specific dietary advice did result in an improvement in LDL cholesterol. Adverse changes in HDL cholesterol and TG because of diet intervention were transient. The significant improvement in glycemic control during the recruitment phase may have been the result of participants' previous dietary knowledge and the increased attention that they received during the intervention.