Low birth weight leads to obesity, diabetes and increased leptin levels in adults: the CoLaus study

Background: Low birth weight is associated with increased rates of obesity, insulin resistance and type 2 diabetes, but the precise mechanisms for this association remain unclear. We aimed to assess the relationships between birth weight and markers of glucose homeostasis or obesity in adults. Methods: Cross-sectional population-based study on 1458 women and 1088 men aged 35-75 years living in Lausanne, Switzerland. Birth weight was self-reported and categorized into <= 2.5, 2.6-3.5, 3.6-4.0 and >4.0 kg. Body composition was assessed by bioimpedance. Leptin and adiponectin levels were measured by ELISA. Results: Women with low birth weight (<= 2.5 kg) had higher levels of fasting plasma glucose, insulin, HOMA, diabetes and metabolic syndrome; a non significant similar trend was seen in men. In both genders, height increased with birth weight, whereas a U-shaped association was found between birth weight and body mass index, waist circumference and body fat percentage. After adjusting for age, smoking status, physical activity and fat mass, an inverse association was found between leptin and birth weight categories: adjusted mean +/- standard error 17.3 +/- 0.7, 16.2 +/- 0.3, 15.6 +/- 0.5 and 14.0 +/- 0.8 ng/dL for birth weight categories <= 2.5, 2.6-3.5, 3.6-4.0 and >4.0 kg, respectively, in women (p < 0.05) and 9.8 +/- 0.8, 9.1 +/- 03, 7.8 +/- 0.4 and 7.7 +/- 0.5 ng/dL in men (p < 0.05). An inverse association was also found between reported birth weight and leptin to fat mass ratio: mean +/- standard error 0.77 +/- 0.04, 0.73 +/- 0.02, 0.69 +/- 0.03 and 0.62 +/- 0.04 in women (p < 0.05); 0.46 +/- 0.05, 0.45 +/- 0.02, 0.39 +/- 0.02 and 0.38 +/- 0.03 in men (p < 0.05). No differences in adiponectin levels were found between birth weight groups. Conclusions: Middle-aged adults born with a low weight present a higher prevalence of diabetes and obesity and also higher leptin levels and leptin to fat mass ratio than adults born with a normal weight. The higher leptin levels and leptin to fat mass ratio among adults born with a low weight might be related to nutritional factors during childhood or to the development of leptin resistance and/or higher leptin production by body fat unit. Subjects born with a low weight should be counselled regarding the risks of developing diabetes and/or cardiovascular disease.