Background & objectives: Foetal undernutrition may have important role in adult insulin resistance and diabetes but insulin kinetics in very early life has not been well studied. The present study was undertaken to determine insulin levels in low birth weight neonates and compare with the levels in normal weight and high birth weight neonates.
Methods: Ten 7 day old children each of low birth weight (< 2500 g, Group 1), normal birth weight (2500-3500 g, Group 2) and high birth weight (> 3500 g, Group 3) selected successively over a period of one month were studied. All children were normally delivered at full term and were not suffering from any major illness. Detailed anthropometry was performed, a 6 h fasting blood sample was obtained for blood glucose, lipids, insulin and C-peptide estimation; 60 min after an intravenous glucose load a second sample was obtained for glucose and insulin. Insulin resistance was calculated using the homeostasis model assessment (HOMA).
Results: Levels of total cholesterol, triglycerides, low density and high density lipoprotein cholesterol and glucose were not significantly different in the three groups. Mean fasting and post-glucose load insulin levels (microU/ml) were 2.78 +/- 2.23 and 3.28 +/- 2.04 in Group 1, 1.67 +/- 1.20 and 2.60 +/- 2.32 in Group 2 and 3.37 +/- 2.08 and 4.40 +/- 3.05 in Group 3 and fasting C-peptide levels (microg/ml) were 0.296 +/- 0.22, 0.208 +/- 0.09 and 0.327 +/- 0.23 respectively. There was no inter-group difference in insulin-glucose ratio, insulin levels adjusted for ponderal index and HOMA indices. A significant inverse quadratic correlation (U-shaped curve) of body weight with insulin (fasting and post-glucose) and C-peptide levels was observed (P < 0.05).
Interpretation & conclusion: Both low and high birth weight term neonates have high fasting and post-glucose insulin levels. This U-shaped trend suggests influence of foetal undernutrition (environmental) as well as genetic factors in these children.