An increased concentration of glucose in the blood.

Gestational diabetes is a disorder characterized by abnormally high levels of blood glucose (also called blood sugar) during pregnancy. Affected women do not have diabetes before they are pregnant, and most of these women go back to being nondiabetic soon after the baby is born. The disease has a 30 to 70 percent chance of recurring in subsequent pregnancies. Additionally, about half of women with gestational diabetes develop another form of diabetes, known as type 2 diabetes, within a few years after their pregnancy.\n\nGestational diabetes is often discovered during the second trimester of pregnancy. Most affected women have no symptoms, and the disease is discovered through routine screening at their obstetrician's office. If untreated, gestational diabetes increases the risk of pregnancy-associated high blood pressure (called preeclampsia) and early (premature) delivery of the baby.\n\nBabies of mothers with gestational diabetes tend to be large (macrosomia), which can cause complications during birth. Infants whose mothers have gestational diabetes are also more likely to develop dangerously low blood glucose levels soon after birth. Later in life, these individuals have an increased risk of developing obesity, heart disease, and type 2 diabetes.

Hyperglycemia in the first month of life due to a genetically determined defect in the structure, secretion and/or function of insulin that resolves spontaneously within nine months of onset.

An increased concentration of hemoglobin A1c (HbA1c), which is the product of nonenzymatic attachment of a hexose molecule to the N-terminal amino acid of the hemoglobin molecule. This reaction is dependent on blood glucose concentration, and therefore reflects the mean glucose concentration over the previous 8 to 12 weeks. The HbA1c level provides a better indication of long-term glycemic control than one-time blood or urinary glucose measurements.

A decreased concentration of C-peptide in the circulation. Since C-peptide is secreted in equimolar amounts to insulin, this feature correlates with reduced insulin secretion.

The presence of autoantibodies (immunoglobulins) in the serum that react against glutamic acid decarboxylase.