Hyperproinsulinaemia and risk of Type 2 diabetes mellitus in women

Aims Our objective was to examine prospectively the associations between fasting plasma proinsulin and the proinsulin/insulin ratio and the incidence of Type 2 diabetes in women. Subjects and methods We designed a nested case‐control study within the Nurses’ Health Study, a cohort of 121 700 US women aged 30–55 years at study inception in 1976. Fasting plasma proinsulin, specific insulin and C‐peptide levels were determined in 183 women with a new diagnosis of diabetes made after blood sampling between 1989 and 1990, and 369 control subjects without diabetes. Results After adjustment for age, body mass index, family history of diabetes and other potential confounders, including HbA1c, the odds ratios for diabetes associated with increasing quartiles of proinsulin were 1.00, 0.85, 2.49 and 5.73 (P for trend: