Mothers who have had gestations 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
birthweight 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.