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

Abstract

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. 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. 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). 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.