Gestational diabetes - One health

Gestational diabetes

Gestational diabetes also known as gestational diabetes mellitus (GDM), is when a woman without diabetes, develops high blood sugar levels during pregnancy. Gestational diabetes generally results in few symptoms; however, it does increase the risk of pre-eclampsia, depression, and requiring a Caesarean section.

Babies born to mothers with poorly treated gestational diabetes are at increased risk of being too large, having low blood sugar after birth, and jaundice. If untreated, it can also result in a stillbirth. Long term, children are at higher risk of being overweight and developing type 2 diabetes. Gestational diabetes is caused by not enough insulin in the setting of insulin resistance. Risk factors include being overweight, previously having gestational diabetes, a family history of type 2 diabetes, and having polycystic ovarian syndrome. Diagnosis is by blood tests.

For those at normal risk screening is recommended between 24 and 28 weeks gestation. For those at high risk testing may occur at the first prenatal visit.Prevention is by maintaining a healthy weight and exercising before pregnancy. Gestational diabetes is a treated with a diabetic diet, exercise, and possibly insulin injections.

Most women are able to manage their blood sugar with a diet and exercise. Blood sugar testing among those who are affected is often recommended four times a day. Breastfeeding is recommended as soon as possible after birth. Gestational diabetes affects 3 to 9% of pregnancies, depending on the population studied. It is especially common during the last third of pregnancy.

It  affects 1% of those under the age of 20 and 13% of those over the age of 44. A number of ethnic groups including Asians, American Indians, Indigenous Australians, and Pacific Islanders are at higher risk. In 90% of people gestational diabetes will resolve after the baby is born. Women, however, are at an increased risk of developing type 2 diabetes

Classification

Gestational diabetes is formally defined as "any degree of glucose intolerance with onset or first recognition during pregnancy". This definition acknowledges the possibility that a woman may have previously undiagnosed diabetes mellitus, or may have developed diabetes coincidentally with pregnancy. Whether symptoms subside after pregnancy is also irrelevant to the diagnosis.

A woman is diagnosed with gestational diabetes when glucose intolerance continues beyond 24 to 28 weeks of gestation. The White classification, named after Priscilla White, who pioneered research on the effect of diabetes types on perinatal outcome, is widely used to assess maternal and fetal risk.

 It distinguishes between gestational diabetes (type A) and pregestational diabetes (diabetes that existed prior to pregnancy). These two groups are further subdivided according to their associated risks and management. The two subtypes of gestational diabetes under this classification system are:

• Type A1: abnormal oral glucose tolerance test (OGTT), but normal blood glucose levels during fasting and two hours after meals; diet modification is sufficient to control glucose levels
• Type A2: abnormal OGTT compounded by abnormal glucose levels during fasting and/or after meals; additional therapy with insulin or other medications is required

Diabetes which existed prior to pregnancy is also split up into several subtypes under this system:

• Type B: onset at age 20 or older and duration of less than 10 years.
• Type C: onset at age 10–19 or duration of 10–19 years.
• Type D: onset before age 10 or duration greater than 20 years.
• Type E: overt diabetes mellitus with calcified pelvic vessels.
• Type F: diabetic nephropathy.
• Type R: proliferative retinopathy.
• Type RF: retinopathy and nephropathy.
• Type H: ischemic heart disease.
• Type T: prior kidney transplant.

An early age of onset or long-standing disease comes with greater risks, hence the first three subtypes.Two other sets of criteria are available for diagnosis of gestational diabetes, both based on blood-sugar levels.

Criteria for diagnosis of gestational diabetes, using the 100 gram Glucose Tolerance Test, according to Carpenter and Coustan:

• Fasting 95 mg/dl
• 1 hour 180 mg/dl
• 2 hours 155 mg/dl
• 3 hours 140 mg/dl

Criteria for diagnosis of gestational diabetes according to National Diabetes Data Group

• Fasting 105 mg/dl
• 1 hour 190 mg/dl
• 2 hours 165 mg/dl

3 hours 145 mg/dl