Mothers who have had gestational diabetes (latent diabetics—LD), as well as those who have produced a large-for-dates baby (LFD) but who were not known to have been diabetic, have raised fasting plasma glucose levels, and these may induce fetal overnutrition. The increased birth weight of babies of obese mothers may also be due to their raised fasting plasma glucose levels.
LD and LFD have normal or raised fasting plasma insulin levels even though they have both decreased insulin secretion to small changes in plasma glucose and normal or increased insulin sensitivity. The high fasting plasma glucose probably results from the decreased insulin-secretory response to glucose. Normal subjects have little day-to-day variation of their fasting plasma glucose, whereas subjects with a high fasting plasma glucose have less precise control.
Although LD and LFD had abnormal insulin responses, they have normal plasma glucagon concentrations that do not correlate with glucose tolerance or insulin sensitivity. The reported abnormalities of glucagon in diabetes are probably a secondary, not a primary, event.