Impaired Microvascular Vasodilatory Function in 3-Month-Old Infants of Low Birth Weight

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Abstract
OBJECTIVE—Low birth weight has been linked to an increased risk of type 2 diabetes and cardiovascular disease in adult life. The fetal insulin hypothesis proposed that a genetic predisposition to insulin resistance may also influence vascular development. Therefore, impaired vascular function may be an intrinsic abnormality in low–birth weight infants that antedates clinical features of the insulin resistance syndrome. RESEARCH DESIGN AND METHODS—Two groups of 3-month-old term infants were included in the study: 17 infants of lowest quartile birth weight (LQBW) and 21 infants of highest quartile birth weight (HQBW). Three aspects of skin microvascular function were examined; response to local heating, response to acetylcholine iontophoresis, and capillary density. RESULTS—Median (interquartile ranges) birth weights of the LQBW and HQBW infants were 3,140 g (2,738–3,254) and 3,920 g (3,750–4,020), respectively. Skin maximal hyperemic response to local heating was 2.14 V (1.68–2.30) in the LQBW group vs. 2.44 V (1.96–2.90) in the HQBW group (P = 0.020), and the endothelium-dependent vasodilatory response was 1.03 V (0.62–1.32) in the LQBW group vs. 0.78 V (0.45–1.32) in the HQBW group (P = 0.297). Capillary density in the LQBW and HQBW groups were 46.3 mm−2 (40.1–53.7) and 44.1 mm−2 (41.7–56.0), respectively (P = 0.736). CONCLUSIONS—Skin maximal hyperemic response was lower in LQBW infants, although no reduction in capillary density or defect in endothelium-dependent vasodilatation was observed. Such a lower maximal hyperemic response in early life in LQBW subjects who are at risk for type 2 diabetes and cardiovascular disease supports the hypothesis that impaired microvascular function is an early antecedent to diabetes in later life.