To understand the increased risk factor, the researchers mated ordinary mice and separated the mothers into a control group that ate as much chow as they wanted throughout their pregnancies and another group that was fully nourished during the first two weeks but undernourished during the third week. At birth, the second group’s babies weighed 23 percent less than the control group.
After delivery, all babies nursed and all mothers ate a full diet and maintained a healthy weight; the previously undernourished mice appeared healthy.
As the young mice matured, their glucose levels began to rise. “By 6 months, these levels had spiked abnormally, to 500 mg/dl – the equivalent of serious, full-blown diabetes in humans,” Dr. Mary-Elizabeth Patti said.
Their insulin levels provided a clue as to what caused these results in the mice. In the prenatally undernourished mice, the insulin secretion stayed about the same, regardless of the glucose level in the bloodstream. “The problem was not insulin resistance. It had something to do with insulin secretion,” Patti said.
Cultures of the beta cells eventually revealed that the undernourished mice responded to glucose abnormally. “They were somehow ‘programmed’ to secrete a limited amount of insulin later in life, no matter what signal they got from glucose,” Patti said.
Based on the study’s results, Patti encouraged people to be aware of the importance of prenatal nutrition and of the importance of those born at a low weight to be sure to exercise and control their weight.