Insulin resistance markers in term, normoweight neonates. The Mérida cohort

Several endocrine regulators are implicated in the development of metabolic syndrome. The aim of our study was to assess normal ranges for glucose, growth hormone (GH), insulin-like growth factor-1 (IGF-1), cortisol, insulin and the yet-to-be-published quantitative insulin sensitivity check index (QUICKI) for newborns and a number of homeostatic model assessment (HOMA)-related equations that have been proposed as indicators of insulin sensitivity (HOMA-S) and insulin resistance (HOMA-R). The study included 115 (54 males, 61 females) singleton, normoweight, Spanish Caucasian neonates delivered without foetal distress from mothers of the Mérida (Spain) Birth Cohort who tested negative in the O’Sullivan screen. Neonatal normal values given as the mean (95% confidence interval) were: glucose, 75.3 mg/dL (68.29–82.29); cortisol, 7.4 μg/dL (6.85–7.97); GH, 16.7 ng/mL (14.87-18.60); insulin, 5.5 μUI/mL (4.12-6.88), IGF-155.2  ng/mL (50.82-59.53); QUICKI, 0.45 (0.43-0.48); HOMA-R, 1.36 (0.84-1.88); HOMA-S, 4.07 (2.66-5.49), the glucose/insulin ratio, 33.6 (24.58-42.67); the insulin/cortisol ratio, 0.8 (0.61-1.05). Hormone ranges (except for cortisol, whose values were lower) were equivalent to those of other studies. Cortisolaemia values cannot be associated with the type of delivery, as only three births (2.6%) were by caesarean section, while 20 (17.4%) were instrumental deliveries. Neonates from the lowest quartile of the insulin/cortisol ratio presented higher (p < 0.001) HOMA-S and QUICKI and lower (p < 0.01) HOMA-R values. The results of our study indicate normal ranges for insulin resistance and sensitivity at birth. The insulin/cortisol ratio at birth appears to be a good early indicator of insulin resistance.