High Fasting Plasma Glucose during Early Pregnancy: A Review about Early Gestational Diabetes Mellitus

Abstract

Fasting plasma glucose (FPG) is nowadays routinely measured during early pregnancy to detect preexisting diabetes (FPG ≥ 7 mmol/L). This screening has concomitantly led to identify early intermediate hyperglycemia, defined as FPG in the 5.1 to 6.9 mmol/L range, also early gestational diabetes mellitus (eGDM). Early FPG has been associated with poor pregnancy outcomes, but the recommendation by the IADPSG to refer women with eGDM for immediate management is more pragmatic than evidence based. Although eGDM is characterized by insulin resistance and associated with classical risk factors for type 2 diabetes and incident diabetes after delivery, it is not necessarily associated with preexisting prediabetes. FPG ≥ 5.1 mmol/L in early pregnancy is actually poorly predictive of gestational diabetes mellitus diagnosed after 24 weeks of gestation. An alternative threshold should be determined but may vary according to ethnicity, gestational age, and body mass index. Finally, observational data suggest that early management of intermediate hyperglycemia may improve prognosis, through reduced gestational weight gain and potential early introduction of hypoglycemic agents. Considering all these issues, we suggest an algorithm for the management of eGDM based on early FPG levels that would be measured in case of risk factors. Nevertheless, interventional randomized trials are still missing.

Initially untreated fasting hyperglycaemia in early pregnancy: prognosis according to occurrence of gestational diabetes mellitus after 22 weeks’ gestation: a case–control study

“…In summary, we have confirmed a clear weakness in some recommendations proposing that FPG in the 5.1-6.9 mmol/l range should be considered for diagnosis of hyperglycaemia at any time during pregnancy [11,12,27]. We show that women with eFHG without risk factors are very unlikely to develop further GDM.…”

“…As women with untreated eFHG who subsequently develop GDM have a poor prognosis despite treatment after OGTT, earlier treatment might reduce adverse outcomes. This remains to be proven, however, in randomized controlled studies [11][12][13]. We also assume that women with FPG between 5.1 and 5.4 mmol/l might benefit from dietary counselling if they are obese, probably with no need to perform self-monitoring of blood glucose.…”

“…However, two studies showed that, despite no initial intervention, < 50% of women with eFHG actually developed GDM after 24 weeks’ gestation . Furthermore, early screening for eFHG might not reduce complications . Lastly, to our knowledge, no study has explored the prognosis of untreated eFHG according to the further development of GDM.…”

Difference in the prevalence of gestational diabetes mellitus according to gestational age at 75‐g oral glucose tolerance test in Japan: The Japan Assessment of Gestational Diabetes Mellitus Screening trial

“…Riskin-Mashiah et al also proposed that the same cut-off fasting PG value of 92-125 mg/dL could be used for GDM diagnosis throughout pregnancy 18 . However, Cosson et al proposed that the cut-off fasting PG value for GDM diagnosis at <24 weeks' gestation was 100-125 mg/dL, rather than 92-125 mg/dL 19 The implementation of a 75-g OGTT at <14 or 14-23 weeks' gestation was associated with low 1-h and 2-h PG levels compared with those observed in 75-g OGTTs carried out at 24-28 weeks' gestation. This finding was consistent with those of previous studies.…”

“…However, Cosson et al . proposed that the cut‐off fasting PG value for GDM diagnosis at <24 weeks’ gestation was 100–125 mg/dL, rather than 92–125 mg/dL.…”