The associations between fetal environment and diabetes risk are likely mediated by the offspring's diminished pancreatic β-cell function or reduced insulin sensitivity. Our ability to distinguish between these mechanisms is impeded by the lack of markers describing an individual's gestational environment. Fingerprints, however, are permanently fixed in the first half of gestation, and increased values of a dermatoglyphic marker that contrasts fingerprint ridge counts between the thumbs and fifth fingers (Md15) have been linked to type 2 diabetes. Among 763 adults without known diabetes from the Dutch Hunger Winter Families Study, we tested the associations of Md15 with homeostatic assessment indices of β-cell function (HOMA-b) and insulin sensitivity (QUICKI). For either outcome index, linear regression models included terms for Md15 tertiles and for maternal history of diabetes as reported by each participant. All models were corrected for sibling pairs and adjusted for age, sex and famine exposures. Increased Md15 was associated with decreased HOMA-b (P = 0.03 for Md15 tertile 3 v. 1) but not with QUICKI. In contrast, maternal history of diabetes was associated with decreased QUICKI (P < 0.001) but not with HOMA-b. Birth weight (available for 520 participants) was positively associated with increased QUICKI (P = 0.04 for birth weight tertile 3 v. 1) but not with HOMA-b. Fingerprint Md15, maternal history of diabetes and birth weight may help to identify specific defects in the control of adult glucose metabolism. Research into the environment associated with Md15 variation may suggest prenatal strategies for optimizing β-cell function in adult life.