Aims/hypothesis: We sought to determine the risk of diabetes and IGT/IFG with grand multiparity.
Subjects, materials and methods: Women, aged > or =25 years, from the Australian Diabetes, Obesity and Lifestyle Study and the Crossroads Undiagnosed Disease Study (a rural study in Victoria, Australia), participated in a household census (response 67 and 70%, respectively), subsequently attending a biomedical examination that included an oral glucose tolerance test (58%  and 69% ).
Results: After adjusting for age, obesity and socio-economic status, diabetes, but not IGT/IFG, was less common among women with a parity of 1 to 2 (odds ratio [OR]=0.64 [0.48-0.84]) and 3 to 4 (OR=0.72 [0.53-0.96]) than in grand multiparous women. This relationship was unrelated to past hysterectomy, use of the oral contraceptive pill or menopausal status.
Conclusions/interpretation: Grand multiparity is associated with an increased risk of diabetes but not of IGT/IFG. We postulate that parity accelerates transition from IGT/IFG to diabetes, more than it does transition from normal glucose tolerance to IGT/IFG.