HIGH JUVENILE BODY HEIGHT AND LOW INSULIN LEVELS AS MARKERS PRECEDINGEARLY DIABETES IN THE BB RAT

Diabetes incidence in BB rats is 60-80% and our aim was to investigate whether it is possible to characterize those rats destined to develop diabetes. While the genetic background as well as the environmental f actors affecting BB-rat littermates are very similar, body weight refl ects some existing variance. The study involved 151 BB rats, and the b ody weight of each animal was measured daily from birth. Thirty-four a nimals became diabetic before 100 days of age, and their body weight s howed a 5-10% increase compared to the non-diabetic animals for each d ay of life from day 1 to day 45 (p values 0.0001 to 0.05). This increa sed body weight in individuals destined for diabetes was seen in both sexes. When investigating whether juvenile body weight has any predict ive value, we found that the incidence of diabetes at 100 days of age increased from 22.5% to 46.7% (p < 0.01) when the heaviest animals in each litter were selected, Insulin content in pancreas was examined at day 10 and 20, and was found to be significantly reduced in the BB ra ts with highest body weight compared with rest of the litter (p = 0.02 and p = 0.0005, respectively). The insulin concentration in periphera l blood was significantly reduced in the BB rats with highest body wei ght at 20 days of age (p = 0.002). When early and late diabetic BB rat s were compared at time of diagnosis regarding blood glucose, degree o f insulitis and number of small and large islets, no significant diffe rences were found between the groups.