Decreased weight gain in BB rats before the clinical onset of insulin-dependent diabetes

Inbred specific pathogen-free diabetes-prone (DP) and diabetes-resistant (DR) BB rats were crossed to produce F₁ and intercrossed to produce F₂ rats. Diabetes segregates in these crosses as a recessive trait on rat chromosome 4. The weight gain of genetically diabetes-prone rats born to F₁ healthy parents was studied to avoid effects of maternal diabetes. The weight gain of the F₂ rats was initially not different from the F₁ parents. The F₂ rats later developing diabetes grew in parallel with their non-affected siblings up until the last 9 days before onset. During these 9 days they showed a decreased weight gain compared to their healthy litter-mates regardless of age. We conclude that decreased weight gain precedes the abrupt clinical onset of diabetes in BB rats and that it may be due to processes associated with the selective loss of β cells.