Gestational Diabetes Mellitus

Pregnancy induces progressive changes in maternal carbohydrate metabolism. As pregnancy advances insulin resistance and diabetogenic stress due to placental hormones necessitate compensatory increase in insulin secretion. When this compensation is inadequate gestational diabetes develops. Pregnancy that occurs in a woman who already has diabetes is termed ‘Pre-Gestational Diabetes Mellitus’. Both these situations are associated with increased maternal and fetal morbidity and rarely mortality. The magnitude of these complications is lesser in woman with GDM than in pre-GDM. Universal screening for GDM is strongly recommended for the population ethnically prone to high prevalence of Type 2 DM. The screening around 24 to 28th week is usually done, but it is ideal to test for glucose intolerance in the early pregnancy itself. In much of the world, a 75 gm glucose tolerance test is performed and GDM is diagnosed if 2 hour PG is > 140 mg/dl. Pregnant women with gestational diabetes have a significantly increased incidence of cesarean section, pre eclampsia and macrosomia. It has also been observed that increasing carbohydrate intolerance in women without GDM also do suffer from these perinatal complications. Medical nutrition therapy is important in the management of GDM. Women who fail to respond to nutrition therapy are advised insulin and the insulin dose is individualized. Pre GDM has to be on insulin throughout pregnancy including pre conception period. A short term intensive care not only results in safe motherhood but also gives a long term pay off in the primary prevention of obesity, IGT and diabetes in the offspring as the ‘Preventive medicine starts before birth’. Diabetes and pregnancy encompasses not only pre gestational diabetes mellitus but also any form of abnormal glucose tolerance during gestation. a. Pre-gestational diabetes: The term pre-gestational diabetes denotes conception in a woman who is already a diabetic. b. Gestational diabetes mellitus (GDM): GDM is defined as any degree of glucose intolerance with onset or first recognition during pregnancy. The definition applies whether insulin or only diet modification is used for treatment and whether or not the condition persists after pregnancy. It does not exclude the possibility that unrecognized glucose intolerance may have antedated or begun concomitantly with pregnancy. The prevalence may range from 1 to 16% of all the pregnancies, depending on the population studied and diagnostic test employed.