Post-natal assessment of gestational diabetes: fasting glucose or full glucose tolerance test?
OBJECTIVE
To determine the performance of a fasting glucose sample compared with a full oral glucose tolerance test for the detection of glucose abnormalities in a diverse ethnic population after gestational diabetes.


METHODS
Oral glucose tolerance test results for women attending post-natal testing over a 10-year (2003-2013) period at St Mary's Hospital, Manchester, UK were reviewed. Demographic data were also extracted from the hospital maternity database.


RESULTS
The average attendance for a post-natal oral glucose tolerance test was approximately 45% over the study period. The prevalence of diabetes was 4.8% (30/629), with a higher rate in women of Asian ethnicity compared with other groups (6.6% vs. 3.5%). The sensitivity for a fasting plasma glucose of ≥ 6.1 mmol/l was 90% (95% CI 74.4-96.5%) for the detection of diabetes and 61% (49.1-71.5%) for the detection of diabetes and/or impaired glucose tolerance, with specificities of 91% (88.8-93.3%) and 93% (91.0-95.2%), respectively. The positive and negative likelihood ratios for diabetes and impaired glucose tolerance were 10.4 (7.8-13.8), 0.11 (0.03-0.32) and 9.2 (6.4-13.3), 0.42 (0.31-0.56), respectively. A fasting plasma glucose threshold of 5.6 mmol/l improved the sensitivity for impaired glucose tolerance (from 61% to 77%), but made no difference to the sensitivity for diabetes.


CONCLUSIONS
The current study has demonstrated that detection of diabetes after gestational diabetes, in an ethnically diverse population using a fasting plasma glucose only, was approximately 90%. Compliance with post-natal screening might improve if women attended for a fasting plasma glucose only; this strategy would identify approximately 90% of cases of diabetes and 40% of cases of impaired glucose tolerance.
Maternal and Fetal Health Research Centre, Manchester Academic Health Science Centre, University of Manchester, Central Manchester NHS Trust, Manchester, UK.
J E
JE
Myers
X
X
Hasan
M J A
MJ
Maresh
D000328:Adult; D016640:Diabetes, Gestational / Q000097:blood* / Q000453:epidemiology; D005215:Fasting / Q000097:blood; D005260:Female; D005951:Glucose Tolerance Test / Q000379:methods; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007231:Infant, Newborn; D011181:Postnatal Care / Q000379:methods*; D011247:Pregnancy; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D006113:United Kingdom / Q000453:epidemiology
D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human