Hyperinsulinemia and metabolic syndrome at mean age of 10 years in black and white schoolgirls and development of impaired fasting glucose and type 2 diabetes mellitus by mean age of 24 years

Abstract

The objective of the study was to evaluate preteen insulin and metabolic syndrome (MS) as independent predictors of impaired fasting glucose (IFG) and type 2 diabetes mellitus (T2DM) in black and white females by mean age of 24 years. This was a prospective cohort study. There were 8 measures of fasting glucose and insulin from mean age of 10 years through mean age of 24 years, and insulin also at mean age of 25 years. Childhood MS was defined by at least 3 abnormal values among waist circumference, triglyceride, high-density lipoprotein cholesterol, blood pressure, and glucose. Hyperinsulinemia was defined by insulin greater than or equal to race-specific 75th percentile. Patients with type 1 diabetes mellitus were excluded. The study was held in schools and in an outpatient clinical center. Participants were schoolgirls (260 white, 296 black). There was no intervention. The outcome measures were IFG (fasting glucose of at least 100 to 125 mg/dL) and T2DM (fasting glucose of at least 126 mg/dL). By the age of 24 years, there were 11 cases of T2DM (2%) and 108 cases of IFG (19%). By the age of 24 years, IFG + T2DM was present in 18% of women (73/412) who had normal insulin-no MS at the age of 10 years vs 28% (34/122) of those with high insulin-no MS at the age of 10 years (P = .014) and 67% (10/15) of those with high insulin + MS at the age of 10 years (P < .0001). By stepwise logistic regression, significant, independent, positive predictors of IFG + T2DM were first insulin measure in childhood, age at last sampling, childhood MS, change in body mass index over 15 years, and, separately, initial glucose of at least 100 mg/dL and average of all insulin quartile ranks over 15 years. The correlation between childhood insulin z score and insulin z score 15 years later was r = .30, P < .0001. Insulin and MS at a mean age of 10 years plus change in body mass index over 15 years, and 15-year average insulin rank independently predict IFG + T2DM by mean age of 24 years, suggesting avenues for primary prevention.