In order to demonstrate the effect of family history (FH) coexisting with obesity in insulin resistance (IR) and secretion in subjects at risk for type 2 diabetes, fasting and 2 h post-glucose load serum glucose and insulin concentrations were measured in 143 individuals, 66 men and 77 women, ages ranging from 18 to 68 years, who were considered at risk but were normoglycemic following ADA criteria. Insulin resistance was estimated using HOMA(IR), basal hyperinsulinemia and I(0)/G(0) ratio. Insulin secretion was estimated by means of HOMA(beta-cell), DeltaI(30-0)/DeltaG(30-0) ratio and the insulin concentration at 30 min post-glucose load (I(30)). Disposition index (DI) was calculated to verify if insulin secretion compensate IR. Obesity in males produced an increase in all the parameters indicative of IR in both groups of individuals, with (FH(+)) or without (FH(-)) family history of diabetes, increase that was more pronounced in those FH(-). This effect was not observed in women. The parameters indicative of insulin secretion showed that only in males the presence of FH(+) was responsible for a significant decrease in insulin secretion, mainly expressed as lower values of HOMA(beta-cell) in obese as well as in non-obese. The I(30) and the ratio DeltaI(30-0)/DeltaG(30-0), although lower, did not reach statistical significance. The DI showed that only when obesity and FH were associated the decrease in insulin secretion was not a compensatory response to the IR present in those individuals. In conclusion, normoglycemic obese and non-obese male subjects of Hispanic (Latinos) origin with a family history of type 2 diabetes present not only IR but impaired insulin secretion, having the obese FH(+) and additional risk like low DI.