The purpose of this study was to investigate the basal metabolic rate (BMR) in 16 professional sportswomen (soccer players) versus 15 sedentary women, as related to the presence (FH+) or absence (FH-) of a family history of type 2 diabetes. The sportswomen, in toto, had a significantly higher BMR than expected from predictive equations (+14.92%). However, the difference was limited only to FH- sportswomen (+18.66%, p<0.0005). FH- sportswomen showed a significantly higher measured BMR than FH+ sportswomen (p<0.005), and FH+ (p=0.058) and than FH- (p<0.05) sedentary women. There were no other significant differences relative to physical, metabolic and plasmatic data between the groups. The sportswomen with familiarity to type 2 diabetes had a BMR lower than that of FH- sportswomen, and similar to that of sedentary sedentary women. It appears that FH+ sportswomen have a "sub-clinical metabolic inertia", representing a precocious signal in young diabetes-prone subjects, despite the modifications induced from activity on their body composition (increased FFM, even though marginally significant).