Long-term (1- and 2-year) effects of lifestyle intervention in type 2 diabetes relatives.

Aims: To study the long-term (1- and 2-year) effect of a lifestyle intervention on non-diabetic first-degree relatives of type 2 diabetic patients, i.e., the 1-year effect of diet versus diet and exercise in relation to a control group and the 2-year sustainability of these treatment effects.

Method: Seventy-seven healthy first-degree relatives (men and women) between the ages of 25 and 55 were allocated to one of three groups: diet group (D), diet and exercise group (DE) and control group (C). For ethical reasons, after 1 year the control group began the intervention and were followed for another 2 years. Diet and physical activity counselling was based on current nutrition recommendations, including increased intake of fatty fish and low glycaemic index foods. The fatty acid composition of the erythrocyte membrane was studied as an objective measure of dietary change. Assessments included fasting insulin, 2-h insulin, oral glucose tolerance test (OGTT), anthropometry and blood lipid measurements. Groups D and DE received intensive follow-up through unannounced telephone interviews during the first 4 months.

Results: Dietary changes were significant at 1 year, and to a large degree sustained at 2 years. Adherence to advice regarding fat quality was confirmed through changes in the fatty acid composition of the erythrocyte membrane. The least active subjects in DE increased their physical activity (PA). At 1 year, group D showed a reduction in the ratio of LDL to HDL cholesterol (p=0.028) while group DE decreased their body weight by 2.7% (p<0.029) and increased HDL (p<0.037) versus controls. At 2 years, cholesterol levels (total, LDL and the ratio LDL/HDL) were reduced within group D and when compared to DE (p=0.022, 0.009, 0.035, respectively). Fasting insulin was reduced within group DE and when compared to group D (p=0.025).

Conclusions: Positive changes in lifestyle, blood lipids and fasting insulin can be achieved and maintained in a non-diabetic population at risk of type 2 diabetes after 2 years.