Association of Parity with Type 2 Diabetes Mellitus in Japan

This study investigates the association between parity and type 2 diabetes mellitus (T2DM) in Japanese women, considering the clinical history of gestational diabetes mellitus (GDM) and menopausal status, which are known risk factors for T2DM. Overall, 30,116 Japanese women (6,588 premenopausal and 23,528 postmenopausal) were included in this cross-sectional study. They were divided into two groups according to menopausal status (premenopausal and postmenopausal women), and the association between parity and T2DM was evaluated using a multiple logistic regression model with possible confounders, including a clinical history of GDM. The association between parity and T2DM was not statistically significant in premenopausal women. In contrast, a linear graded association between parity and T2DM was found in postmenopausal women. Furthermore, the association between parity and T2DM in postmenopausal women was attenuated after adjusting for body weight gain after the age of 20 years. A clinical history of GDM was significantly associated with a high risk for T2DM, regardless of adjustment for body weight gain after the age of 20 years in both premenopausal and postmenopausal women. Parity is associated with an increased risk of T2DM in postmenopausal women but not in premenopausal women. Maintaining appropriate body weight would be beneficial in attenuating the risk of T2DM in postmenopausal women. A clinical history of GDM is a risk factor for T2DM in both pre- and postmenopausal women; therefore, women with a clinical history of GDM require continuous medical care to survey for T2DM.