The findings of the lowest HOMA-β in group 3 and 4, and the slightly increased tendency of HOMA-IR in group 4 than group 1 NGT subjects suggest that decreased insulin secretion due to advancing maternal age is primarily responsible, and increased insulin resistance due to obesity might have additive effects, for the FAO observed in the older NGT women with or without obesity. This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.