Physical activity, diet, and incident diabetes in relation to an ADRA2B polymorphism

PURPOSE: The 12Glu9 polymorphism of the alpha2B-adrenergic receptor gene may impair insulin secretion and modify the effects of a lifestyle intervention on the risk of type 2 diabetes, but the interaction with specific lifestyle components is unknown. We assessed the associations of leisure-time physical activity (LTPA), dietary changes, and weight loss on the risk of type 2 diabetes according to the 12Glu9 polymorphism in 481 participants of the Finnish Diabetes Prevention Study. METHODS AND RESULTS: The lifestyle intervention decreased the risk of diabetes in 9Glu carriers (9Glu9, intervention vs control, relative risk (RR) = 0.23, 95% confidence interval (CI) 0.09-0.62), but not in 12Glu12 homozygotes. In the combined intervention and control groups, increased total LTPA as estimated with a questionnaire decreased the risk of diabetes in 12Glu carriers (12Glu12, upper vs lower third, RR = 0.12, 95% CI 0.03-0.53) but not in 9Glu9 homozygotes (P for the interaction 0.033). In contrast, favorable dietary changes, estimated using a dietary score, reduced the risk of diabetes in those with the 9Glu9 genotype (upper vs lower third, RR = 0.21, 95% CI 0.06-0.75) but not in those with the 12Glu allele. Weight loss significantly decreased the risk of diabetes only in 12Glu carriers. CONCLUSION: Increased LTPA decreased the risk of type 2 diabetes more in those with the 12Glu allele of the ADRA2B gene, whereas dietary changes may have mediated the greater risk reduction of the lifestyle intervention in 9Glu homozygotes.