Association between parental history of diabetes and the incidence of type 2 diabetes mellitus differs according to the sex of the parent and offspring's body weight: A finding from a Japanese worksite-based cohort study.

Objective: To investigate differences in the association of parental history of diabetes with the risk of type 2 diabetes mellitus (T2DM) in the offspring according to the sex of the parent and the offspring's body weight.

Methods: A prospective cohort study of 4446 middle-aged non-diabetic Japanese men and women were followed in Aichi Prefecture, central Japan, from 2002 to 2011. Subjects were categorized by their self-reported parental history of diabetes ("no parental history," "father only," "mother only," and "both"). The association of parental history of diabetes and incidence in the offspring was examined according to overweight status adjusted for age, sex, birth weight, smoking, alcohol consumption, physical activity, total energy intake, body mass index, and number of metabolic syndrome components.

Results: During follow-up (median 8.9 years), 277 subjects developed T2DM. Parental history of diabetes was positively associated with T2DM incidence. However, stratified analysis by overweight status revealed that only maternal history was associated with increased T2DM incidence in non-overweight subjects (hazard ratio=2.35, 95% confidence interval: 1.41-3.91). While in overweight subjects, paternal history was significantly associated with higher T2DM incidence (hazard ratio=1.98, 95% confidence interval: 1.19-3.28).

Conclusions: Our results suggest that parental history of diabetes mellitus is associated with the incidence of T2DM in offspring differently according to the sex of the affected parent and the offspring's body weight.