Absence of pregnancy-induced alterations in tissue insulin sensitivity in the offspring of diabetic rats.

We have previously demonstrated insulin resistance in the liver and peripheral tissues of the adult offspring of rats made diabetic with streptozotocin (SDF rats). In this study, a euglycaemic hyperinsulinaemic clamp was used to test the hypothesis that insulin resistance is further aggravated during pregnancy in SDF rats. Normal pregnancy was accompanied by a decrease in the sensitivity of the liver and peripheral tissues to insulin, with a normal responsiveness to insulin. In SDF rats no further decrease in the sensitivity of peripheral tissues to insulin occurred during pregnancy when compared with non-pregnant rats, and the dose-response curves of the glucose metabolic clearance rate during hyperinsulinaemia were similar in pregnant control and pregnant SDF rats. There was, however, a modest decrease in the sensitivity of the liver to insulin during pregnancy in SDF rats. The normal increase in plasma insulin levels during pregnancy was blunted in SDF rats: this resulted in increased glucose levels in maternal and fetal rats and increased fetal insulin concentrations, features compatible with mild 'gestation diabetes'. In conclusion, gestational diabetes develops in pregnant SDF rats, although there is no further deterioration in peripheral insulin resistance.