To verify whether a diabetes family history might be a risk factor for the development, in adult age, of metabolic disorders, leptin, anthropometric and endocrine parameters were analysed in 95 babies with grandparents affected by type 2 diabetes (DF) and in 95 matched babies without diabetes family history (NDF). A sexual dimorphism for leptin was present in the NDF group (males: 6.7+/-4.1 ng/ml; females: 12.3+/-6.5; p < 0.0001) but not in the DF group (males: 9.0+/-5.5; females: 10.8+/-6.4), due to the significant increase in DF male leptin level, compared to that of NDF males (p < 0.05). In DF males only, leptin was positively correlated with body length, PI, C-peptide, IGF-1 and IGF1BP3. These results suggest that the increase in DF male leptin could be a compensatory mechanism for reduced insulin sensitivity in a pre-clinical alteration of glucose metabolism.