Quantification of the type 2 diabetes risk in women with gestational diabetes: a systematic review and meta-analysis of 95,750 women

Rayanagoudar G, Hashi AA, Zamora J, et al.
Diabetologia (2016) 59:1403–1411

Background

Gestational diabetes mellitus (GDM), defined as glucose intolerance diagnosed for the first time during pregnancy, reveals females at high risk of developing type 2 diabetes mellitus (T2DM), which becomes evident within the first 5 years after pregnancy in half of all cases [1,2]. Follow-up of women with GDM, as recommended by medical guidelines, is suboptimal, since less than a fifth of all cases undergo postpartum glucose screening [3-6]. Personalised risk quantifications may increase the number of individuals that achieve compliance, however only few prediction models for T2DM include GDM and none include pregnancy-specific characteristics [7].
In this systematic review and meta-analysis of 39 studies including 95,750 women, the risk of females with GDM to develop T2DM was quantified.

Main results

• A high BMI doubled the risk of future T2DM significantly (RR: 1.95; 95% CI: 1.60 - 2.31; I² = 65%), and the risk was significantly increased in obese and overweight women for BMI thresholds of 25 kg/m² (RR: 3.18; 95%CI: 1.96 - 5.16; I²=77%), 27 kg/m² (RR: 2.52; 95% CI: 1.69 - 3.74; I²=23%) and 30 kg/m² (RR: 2.85; 95% CI: 2.21 - 3.69; I²=45%).
• A family history of diabetes (RR: 1.70; 95% CI: 1.47 - 1.97; I²=13%), non-white ethnicity (RR: 1.49; 95% CI: 1.14 - 1.94; I²=88%), older age (RR: 1.20; 95% CI: 1.09 - 1.34; I²=0%), and gestational age (RR: 2.13; 95% CI: 1.52-3.56; I²=64%) were associated with a higher risk for the progression of GDM to T2DM.

• Blood glucose levels after an oral glucose tolerance test were associated with significantly increased risk of future T2DM (fasting RR: 3.57; 95% CI: 2.98 - 4.04; I² =90%, 1 h RR: 3.05; 95% CI: 2.40 - 3.63; I² = 64%, 2 h RR: 3.46; 95% CI: 2.60 - 4.10; I² = 80%, 3 h RR: 3.2; 95% CI: 2.54 - 3.75; I² = 65%).
• High HbA1c was also significantly associated with an increased risk of future diabetes (RR: 2.56; 95% CI: 2.00 - 3.17; I²=54%).
• Women who required insulin for GDM were more likely to develop T2DM (RR: 3.66; 95% CI: 2.78 - 4.82; I² = 71%, P<0.001) compared with those who did not need insulin.

• Women with hypertensive disease (RR: 1.38; 95% CI: 1.32 - 1.45; I² =0%, P<0.001) or preterm delivery (<37 weeks) (RR: 1.81; 95% CI: 1.35 - 2.43; I² = 0%, P<0.001) were more likely to develop T2DM in the future.

Conclusion

In females with GDM, the future risk of T2DM mainly depends on the gestational glycaemic status, hypertensive disorders during pregnancy, and preterm delivery, as well as gestational age at onset of GDM, BMI, ethnicity and family history. These data should be used for post-natal counselling of women with GDM.

Find this article online at Diabetologia

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