Gestational Diabetes - Classification

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 patients 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 of having gestational diabetes when the glucose intolerance continues beyond 24-28 weeks of gestation.

The White classification, named after Priscilla White, who pioneered in 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 diabetes that existed prior to pregnancy (pregestational diabetes). These two groups are further subdivided according to their associated risks and management.

The two subtypes of gestational diabetes (diabetes which began during pregnancy) 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

The second group of diabetes which existed prior to pregnancy is also split up into several subtypes.

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. Criteria for diagnosis of gestational diabetes according to Carpenter and Coustan

Fasting 95mg/dl

1 hour 180mg/dl

2 hours 155mg/dl

3 hour 140mg/dl

Criteria for diagnosis of gestational diabetes according to Indian National Diabetes Data group

Fasting 105mg/dl

1 hour 190mg/dl

2 hours 165mg/dl

3 hour 145mg/dl