What is the efficacy of 2-step screening for gestational diabetes mellitus (GDM)?

Updated: Apr 29, 2020
  • Author: Thomas R Moore, MD; Chief Editor: George T Griffing, MD  more...
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Meltzer et al found that 2-step screening with a 1-hour, 50-g glucose screen, followed by (if necessary) an OGTT, was superior to 1-step screening with a 75-g OGTT. In a prospective, randomized, controlled trial, the total cost per woman screened was lower with the 2-step approach, because many patients with gestational diabetes were diagnosed on the basis of a glucose screen result of 10.3 mmol/L (185.4 mg/dL) or greater, thus obviating the additional blood draws and time required for the OGTT. [63]

Similarly, an analysis of data on 64,687 pregnant women with no preexisting diabetes indicated that a diagnosis of gestational diabetes mellitus can sometimes be made just on the basis of a GCT. In the study, the women were screened for gestational diabetes mellitus over 16 years in 2 regions of a large US health plan. Overall, 2% of the women in the study needed insulin, ranging from 0.1% of those with normal GCT results to 49.9% of those with a GCT result of over 200 mg/dL. [64, 65]

Other tests (eg, maternal HbA1C, random postprandial or fasting blood sugar level, or fructosamine level) are not recommended because of low sensitivity.

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