Maternal diabetes during pregnancy still carries a risk of malformed and spontaneously aborted offspring. Besides, recently there has been obtained epidemiological evidence for the long term effects on adult health of altered ‘programming’ during a sensitive period of early life, where stimulus or insult at a critical, sensitive period of early life has permanent effects on structure, physiology and metabolism. Since besides intrauterine hyperglycaaemia, the offspring of a diabetic mother could be affected by altered lactation as a consequence of the known decreased milk yield of the mother, the present study has addressed the long term consequences of changes in the suckling schedule of newborns of diabetic rats.

At day 8 of pregnancy, some rats were made diabetics by treatment with 5 mg of streptozotocin (STZ)/100 g b.w. (D), whereas controls (C) were treated with medium (50 mM citrate buffer, pH 4.5). At the time of delivery the litters were unified to five pups per dam and they were distributed among four groups as follows: (i) pups from C mothers that were allowed to suckle from C dams (cC); (ii) pups from D mothers that were allowed to suckle from C dams (dC); (iii) pups from C mothers that were allowed to suckle from D dams (cD); and (iv) pups from D mothers that were allowed to suckle from D dams (dD). Pups were weighed at birth and at 20, 30 and 60 days of age. At 60 days of age, an oral glucose tolerance test (OGTT) was performed in all the pups, as follows: blood was collected from the tail (time 0), and rats received an oral load of 2 g glucose per kg b.w., blood being also collected from the tail 15, 30 and 60 min thereafter, and glucose, insulin, triglycerides (TG) and free fatty acids (FFA) were measured in plasma aliquots. At the end of the experiments, all animals were humanely killed. Statistical analysis was performed by ANOVA or the Mann-Whitney test as appropriate. P < 0.05 was considered significant.

At birth, dC and dD pups weighed less than cC and cD pups. Besides, whereas dC pups completely recovered their body weight, attaining values that did not differ to cC, the increase of body weight and size of cD pups were lower than in cC, attaining statistically significant differences. In dD pups, the increase in both plasma glucose and insulin in the OGTT were smaller than in any of the other groups, whereas in dC pups basal glucose (time 0) was higher and in cD plasma insulin at 0 and 15 min time was lower than the other groups but plasma glucose did not differ.

Thus although the present findings show long term consequences of the intrauterine diabetic milieu on growth and in the glucose/insulin axis, they also show that changes in dietary conditions during suckling also affect these variables even in pups from control dams.