Rate of Postpartum Diabetes Screening May Be Low

From Medscape Medical News
Laurie Barclay, MD Charles P. Vega, MD

Diabetes Care. Published online September 9, 2009. Abstract

Clinical Context

Gestational diabetes is associated with an increased risk for the subsequent development of type 2 diabetes, and a previous systematic review by Kim and colleagues explored this relationship. Their findings, which were published in the October 2002 issue of Diabetes Care, suggested that the lifetime incidence of type 2 diabetes among women with a history of gestational diabetes could be more than 70%. The risk for incident diabetes is highest in the first 5 years after delivery and plateaus by 10 years. An elevated fasting glucose level was the most important factor in predicting the risk for incident diabetes.

Nonetheless, many women at risk for incident diabetes do not receive testing for hyperglycemia in the postpartum period. The current study examines the prevalence of such testing and compares oral glucose tolerance testing vs fasting glucose testing in diagnosing hyperglycemia.


Study Highlights

The study design was a retrospective cohort review of cases from 1 hospital in Canada. The researchers focused on women with a history of gestational diabetes or impaired glucose tolerance during pregnancy.
Gestational diabetes was diagnosed after a 50-g oral glucose tolerance test result of 10.3 mmol/L or more at 1 hour, or after an abnormal 2-hour glucose tolerance test result after an equivocal 1-hour result. Impaired glucose tolerance was defined as a fasting plasma glucose level of 5.3 mmol/L or more, a 1-hour result of 10.6 mmol/L or more, or a 2-hour result of 8.9 mmol/L or more after a 75-g oral glucose tolerance test.
Women with a history of hyperglycemia before pregnancy were excluded from study analysis.
Researchers examined the prevalence of screening for diabetes postpartum and compared oral glucose tolerance testing vs fasting plasma glucose testing in diagnosing hyperglycemia.

Diabetes was defined as a fasting plasma glucose level of 7 mmol/L or more, or a 2-hour glucose level of at least 11.1 mmol/L after a 75-g oral glucose tolerance test. Impaired glucose tolerance was defined as a 2-hour glucose level of 7.8 to 11.1 mmol/L after a 75-g oral glucose tolerance test. Impaired fasting glucose was defined as a glucose level between 6.1 and 6.9 mmol/L.
909 women underwent analysis. The mean age of subjects was 31.7 years, and two thirds of the cohort had a family history of diabetes. A total of 61% of women had used insulin during pregnancy.
Only 438 (48.2%) of women underwent postpartum testing, of whom 21 completed only a fasting plasma glucose test.
Women with a higher parity and who did not use insulin were less likely to receive postpartum glucose testing.
14 women were diagnosed with type 2 diabetes at the postpartum visit, whereas 15 had impaired fasting glucose, 57 had impaired glucose tolerance, and 3 had both impaired glucose tolerance and impaired fasting glucose.
Results of the fasting plasma glucose test and oral glucose tolerance test were abnormal in 5.7% and 21.3% of women, respectively. Fasting glucose testing alone would have missed 72% of women with an abnormal glucose result.
Non-Caucasian ethnicity, previous gestational diabetes, and higher pregnancy oral glucose tolerance testing values were all predictors of a higher risk for an abnormal postpartum glucose testing result.

Clinical Implications

A previous systematic review found that the lifetime incidence of type 2 diabetes among women with a history of gestational diabetes may exceed 70%.

The rate of new cases of diabetes was highest in the first 5 years after delivery. Although a high fasting glucose test result during pregnancy was found to be an important predictor of the risk for type 2 diabetes, race alone was not.
Less than half of women with abnormal glucose testing results during pregnancy received postpartum glucose screening in the current study. Oral glucose tolerance testing was more sensitive than fasting plasma glucose testing in diagnosing postpartum glucose abnormalities.