This study was designed to evaluate the effects of chronic endurance training on glucose and lipid homeostasis in diabetic mothers and their offspring. Female Sprague-Dawley rats were rendered diabetic (>20 mmol/l glucose) by streptozotocin and subdivided into three treatments (n = 10/group): exercise (20 m/min; 0% grade; 1 h/day; 5 days/wk) before and during gestation (EE), exercise before gestation with cessation on conception (ES), and sedentary before and during gestation (SS). Response of dams to a preconception and third trimester glucose tolerance test, litter number (EE = ES = SS = 3), and average litter size (EE = 9.7 +/- 1.5; ES = 9.0 +/- 1.5; SS = 8.3 +/- 0.3) did not differ among groups. Number of offspring remaining viable was significantly different among groups (EE = 17; ES = 0; SS = 14). Response to a glucose challenge and fasting glucose and insulin were different between the EE and SS pups. Exercise before and during gestation did not reduce the viability of offspring. Cessation of exercise during early pregnancy negatively affected offspring viability.