What is the rate of gestational diabetes in twin pregnancies compared to singleton pregnancies?

Gestational Diabetes in Twin Pregnancies: Incidence and Comparison to Singleton Pregnancies

Twin pregnancies have approximately twice the risk of developing gestational diabetes mellitus compared to singleton pregnancies, with rates of 7.7-9.6% in twins versus 4.1-7.6% in singletons. 1, 2, 3

Epidemiology and Risk Factors

• Twin pregnancies show a significantly higher incidence of gestational diabetes mellitus (GDM) compared to singleton pregnancies:

  • 7.7% vs 4.1% (p<0.05) 1
  • 9.6% vs 7.6% 2
  • 3.98% vs 2.32% (p=0.01) 3

• After adjusting for confounding variables (age, race/ethnicity, BMI, blood pressure, smoking, parity), twin pregnancy is associated with approximately twice the risk for developing GDM (OR 2.2,95% CI 1.4-3.6) 3

• Highest risk groups for GDM in twin pregnancies:

  • Women between ages 25-30 years
  • African-American women 3

Pathophysiology

• The increased risk of GDM in twin pregnancies is likely due to greater insulin resistance associated with carrying multiple fetuses 4

• Twin pregnancies demonstrate significantly higher 3-hour glucose tolerance test values compared to singleton pregnancies, indicating more pronounced glucose metabolism disturbances 1

• However, insulin requirements for management are not significantly different between twin and singleton GDM pregnancies, suggesting a milder disturbance of carbohydrate tolerance that responds well to standard management approaches 1

Clinical Implications and Outcomes

Maternal Outcomes

• GDM in twin pregnancies is associated with:

  • Increased risk of cesarean delivery (adjusted RR 1.11 [1.02-1.21]) 5
  • Higher rates of preterm birth at <37 weeks (adjusted RR 1.21 [1.08-1.37]) and <34 weeks (adjusted RR 1.45 [1.03-2.04]) 5

• Unlike in singleton pregnancies, GDM in twins is NOT associated with:

  • Gestational hypertension
  • Preeclampsia 5

Fetal/Neonatal Outcomes

• GDM in twin pregnancies is associated with:

  • 2.5-fold increased risk of birthweight >90th percentile (adjusted RR 2.53 [1.52-4.23]), which is twice the risk seen in singletons with GDM 5
  • Increased risk of neonatal jaundice (adjusted RR 1.56 [1.10-2.21]) 5
  • Higher rates of NICU admission (37% vs 52%, p=0.05) 3
  • Longer hospital stays (8±0.5 vs 16±4 days, p=0.01) 3
  • Increased respiratory distress syndrome (7% vs 27%, p=0.001) 3

• Unlike in singleton pregnancies, GDM in twins is NOT associated with:

  • NICU admission (except as noted above)
  • Respiratory morbidity
  • Neonatal hypoglycemia 5

Fetal Growth Patterns

• In contrast to singleton pregnancies where GDM is consistently associated with accelerated fetal growth starting around 30 weeks, twin pregnancies with diet-controlled GDM generally show similar growth patterns to non-GDM twin pregnancies 2

• Accelerated fetal growth in twin pregnancies with GDM is primarily observed only in the subgroup requiring medical treatment (insulin or oral agents), which represents approximately 12% of twin pregnancies with GDM 2

Clinical Considerations

• Current diagnostic criteria and management approaches for GDM in twin pregnancies are based on singleton pregnancy standards, which may not be optimal 4

• Some evidence suggests that the increased insulin resistance in twin pregnancies may represent a physiological adaptation rather than pathology, particularly in diet-controlled cases 4

• Strict glycemic control in diet-treated GDM twin pregnancies might potentially increase the risk of intrauterine growth restriction 4

• Twin-specific screening and diagnostic criteria for GDM may be needed, with preliminary data suggesting higher optimal thresholds than those used for singleton pregnancies 4

Monitoring Recommendations

• Multiple gestations require more intensive monitoring than singleton pregnancies, including:

  • First trimester dating scan
  • Nuchal translucency scan at 11-14 weeks
  • Anatomy scan at 18-22 weeks
  • One or more third-trimester growth scans 6

• Twin pregnancies with GDM should be monitored with particular attention to fetal growth patterns, as the impact of GDM on growth differs from singleton pregnancies 2

Pitfalls and Caveats

• Overdiagnosis of GDM in twin pregnancies may occur when using singleton criteria, potentially leading to unnecessary interventions 4

• Overtreatment with strict glycemic targets might increase the risk of intrauterine growth restriction in twins 4

• The higher baseline risk of complications in twin pregnancies (preterm birth, growth restriction) may mask or modify the typical GDM-associated complications seen in singleton pregnancies 5, 4