Beta-cell hyperplasia in macrosomic infants and fetuses of nondiabetic mothers.

The objective of this study was to test the hypothesis that macrosomic infants of nondiabetic mothers have beta-cell hyperplasia in their pancreases. Pancreatic tissues were examined from 10 macrosomic fetuses and liveborn infants and from 10 comparison cases matched for gestational age and gender. None of the mothers had a history of diabetes and all had normal glucose screening during pregnancy. Tissues were stained with hematoxylin and eosin and a monoclonal antibody against beta cells and were analyzed using an image analysis program to evaluate the size and surface area of beta-cell clusters. Brain/liver weight ratios were calculated and compared. The total surface area and cluster size of beta cells in the pancreases of macrosomic subjects were significantly larger than in the comparison pancreases. The study subjects lacked macroscopic and histopathologic findings expected in infants of diabetic mothers. We conclude that some macrosomic fetuses and infants of nondiabetic mothers manifest beta-cell hyperplasia. This corresponds to the higher insulin levels in macrosomic infants of nondiabetic mothers described in previous clinical studies. In macrosomic fetuses the stimulus for beta-cell hyperplasia may not involve aberrant maternal glucose levels.