Non-diabetic relatives of Type 2 diabetic families: dietary intake contributes to the increased risk of diabetes

Aims Non-diabetic first degree relatives of Type 2 diabetic patients are at increased risk of developing diabetes and cardiovascular disease. This is assumed to reflect a shared genetic predisposition. The aim of this study was to test the hypothesis that lifestyle factors, specifically dietary factors, are also important to the increased risk in non-diabetic relatives. Methods Dietary intake was assessed using a validated food frequency questionnaire in 149 non-diabetic first degree relatives (age 20-65 years) from families of North European extraction with two or more living Type 2 diabetic family members, and 143 age- and sex-matched control subjects from the background population with no family history of diabetes. Results Relatives reported higher absolute intakes of total fat (mean (95% confidence intervals) 83 (76-91) vs. 71 (66-76) g/day, P = 0.01), saturated fat (SFA; 39 (36-43) vs. 33 (30-36) g/day, P < 0.01) and cholesterol (391 (354-427) vs. 318 (287-349) mg/day, P < 0.01), and a lower intake of non-starch polysaccharide (P < 0.05). Considered as percentage of total daily energy intake, relatives had higher intakes of total fat (P < 0.01) and SFA (P < 0.02), and a lower intake of carbohydrate (P < 0.02). These differences remained after exclusion of suspected under- and over-reporters of dietary intake. Conclusions Non-diabetic relatives of Type 2 diabetic patients were found to consume diets that will promote rather than prevent the development of diabetes and cardiovascular disease. This suggests that the increased risk to non-diabetic relatives is therefore not entirely genetic, and there is scope for decreasing the risk through lifestyle modification.