In this study, 30 kits from 5 litters, 1 male and 1 female from each, were allocated to 3 feeding regimes: 80, 100 or 120% of the recommended dietary allowance (RDA) of metabolizable energy (ME). The mink were weighed (body weight, BW), scored for body condition (BCS, scale 1-5, 3=ideal) and sampled for blood and urine monthly from mid-August to mid-December. In December, 6/10 mink in the 100% RDA group scored 3, while in the 80% RDA group 7/10 mink received a BCS of 2 (thin) and in the 120% RDA group 8/10 mink had a BCS 4-5 (heavy-obese, P<0.001). The final blood glucose levels of all mink in the 120% RDA group were higher (6.59 mmol/litre) in comparison to the 80% RDA (5.21 mmol/litre) and the 100% RDA groups (4.95 mmol/litre, SEM=0.37, P=0.01). The males in the 120% RDA group showed hyperinsulinaemia (2.06 ng/ml, SEM=0.164, P=0.043) in comparison to the other groups (1.17-1.51 ng/ml). No glucosuria was detected. The development of obesity appears to be associated with elevated blood glucose concentrations and hyperinsulinaemia in the mink, suggesting insulin resistance.