One such is the ‘thrifty (fetal) insulin hypothesis’, which proposes that low birthweight and type 2 diabetes mellitus (T2DM) are two phenotypes of the same genotype that also predicts insulin resistance.6 The ‘thrifty phenotype’ hypothesis is supported by a substantial body of research in animal models, and by observational studies.7 Here, INS is linked to type 2 diabetes mellitus.