Birth size and risk of insulin-dependent diabetes mellitus (IDDM).

A case-control study was conducted to test the hypotheses that birth size is increased in infants who develop IDDM in childhood and that birth size differs by diagnosis age. Cases were non-Hispanic white (NHW) children randomly selected from the Colorado IDDM Registry (n = 221). Controls (n = 197) were NHW children frequency-matched to cases by age-group and gender. Self-administered questionnaires collected birth size and demographic data. There were no significant univariate differences in birth weight (cases 3303.0 g; controls, 3346.1 g; P = 0.40), birth length (cases, 50.8 cm; controls, 51.2 cm; P = 0.28), or ponderal index (cases, 2.52; controls, 2.49; P = 0.92). The case/control odds ratio (OR) controlling for gender, maternal education, and birth place was 1.0 (95% confidence interval (CI) 0.4, 2.5) for the highest category of birth weight compared to the lowest. There were no statistically significant case/control differences in ponderal index (highest to lowest category OR = 1.1; 95% CI 0.6, 2.0) or birth length (1 cm increase OR, 1.0; 95% CI 0.9, 1.2). Similarly, analysis by age-at-diagnosis groups revealed no significant differences, suggesting that birth size does not reveal prenatal diabetogenic influences.