Diagnosis of gestational diabetes mellitus: falling through the net.

Claire L Meek,Helen R Murphy,Charlotte Patient,Hannah B Lewis,David Simmons

doi:10.1007/s00125-015-3647-z

Abstract

Aims/hypothesisGestational diabetes mellitus (GDM) is associated with increased risks to mother and child, but globally agreed diagnostic criteria remain elusive. Identification of women with GDM is important, as treatment reduces adverse outcomes such as perinatal death, shoulder dystocia and neonatal hypoglycaemia. Recently, the UK’s National Institute for Health and Care Excellence (NICE) recommended new diagnostic thresholds for GDM which are different from the International Association of the Diabetes and Pregnancy Study Groups (IADPSG) criteria endorsed by the WHO. The study aim was to assess neonatal and obstetric outcomes among women who would test positive for the IADPSG criteria but negative for the NICE 2015 criteria.MethodsData from 25,543 consecutive singleton live births (2004–2008) were obtained retrospectively from hospital records. Women were screened with a random plasma glucose (RPG; 12–16 weeks) and a 50 g glucose challenge test (GCT; 26–28 weeks). If RPG >7.0 mmol/l, GCT >7.7 mmol/l or symptoms were present, a 75 g OGTT was offered (n = 3,848).ResultsIn this study, GDM prevalence was 4.13% (NICE 2015) and 4.62% (IADPSG). Women who ‘fell through the net’, testing NICE-negative but IADPSG-positive (n = 387), had a higher risk of having a large-for-gestational-age (LGA) infant (birthweight >90th percentile for gestational age; adjusted OR [95% CI] 3.12 [2.44, 3.98]), Caesarean delivery (1.44 [1.15, 1.81]) and polyhydramnios (6.90 [3.94, 12.08]) compared with women with negative screening results and no OGTT (n = 21,695). LGA risk was highest among women with fasting plasma glucose 5.1–5.5 mmol/l (n = 167): the mean birthweight was 350 g above that of the reference population and 37.7% of infants were LGA.Conclusions/interpretationThe IADPSG criteria identify women at substantial risk of complications who would not be identified by the NICE 2015 criteria.

Highlights

Gestational diabetes mellitus (GDM), defined as carbohydrate intolerance causing hyperglycaemia with first onset or recognition in pregnancy [1, 2], is increasing in incidence in many populations worldwide as obesity becomes more prevalent [3]
Untreated GDM results in poor maternal and fetal outcomes: women with GDM are more likely to suffer preeclampsia, operative delivery and stillbirth [4], and infants are at higher risk of preterm delivery and macrosomia or large for gestational age (LGA), which is associated with birth injury, respiratory distress and neonatal hypoglycaemia [5]
Records were obtained for 25,789 births; 25,543 records were included in the analysis after exclusion of pregnancies resulting in miscarriage (n=59) or termination (n=65), those with no birthweight information (n=3), duplicate data (n=20) and records consistent with overt diabetes (RPG ≥11.1 mmol/l at booking; n=99)

Summary

Introduction

Gestational diabetes mellitus (GDM), defined as carbohydrate intolerance causing hyperglycaemia with first onset or recognition in pregnancy [1, 2], is increasing in incidence in many populations worldwide as obesity becomes more prevalent [3]. Children born to mothers with GDM are at greater risk of obesity and type 2 diabetes in later life, a phenomenon attributed to the effects of intrauterine exposure to hyperglycaemia [6, 7] Many of these risks can be reduced by identification of GDM pregnancies and prompt intervention to reduce maternal antenatal hyperglycaemia [8, 9]. The International Association of the Diabetes and Pregnancy Study Groups (IADPSG) proposed diagnostic criteria which were based upon an OR of 1.75 for negative pregnancy outcomes (Table 1) using data from the Hyperglycaemia and Adverse Pregnancy Outcomes (HAPO) study (75 g OGTT 0 h ≥5.1 mmol/l, 1 h ≥10.0 mmol/ l, 2 h ≥8.5 mmol/l) [10, 11] These criteria used lower fasting plasma glucose (FPG) thresholds than other criteria in common use (Table 1) and added a 1 h criterion, leading to concerns about increased diagnosis rates, resource allocation and increased medicalisation of pregnancy [12, 13]. NICE proposed alternative criteria for adoption in 2015 (75 g OGTT 0 h ≥5.6 mmol/l; 2 h ≥7.8 mmol/l) [15]

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