What percentage of women with a history of gestational diabetes (GDM) go on to develop type 2 diabetes (T2D)?

Risk of Type 2 Diabetes After Gestational Diabetes

Women with a history of gestational diabetes have a 50-60% lifetime risk of developing type 2 diabetes, with risk increasing progressively over time: approximately 20% at 10 years, 30% at 20 years, 40% at 30 years, 50% at 40 years, and 60% at 50 years after the GDM pregnancy. 1, 2

Magnitude of Risk

• Women with GDM have a 10-fold increased risk of developing type 2 diabetes compared to women without GDM 1, 2
• The relative risk is estimated at 8.3 times higher (95% CI 6.5-10.6) compared to women without GDM 3
• Approximately one-third of women develop diabetes within 15 years after a GDM pregnancy 3
• Some studies report that approximately 50% of mothers with GDM will develop diabetes within 10 years, making GDM one of the strongest predictors of type 2 diabetes 4

Factors That Modify Risk

Multiple affected pregnancies dramatically increase risk:

• Having GDM in two pregnancies significantly increases risk compared to a single GDM pregnancy, with hazard ratios ranging from 4.35 to 15.8-fold 2
• Risk increases substantially with each additional affected pregnancy 5

Body weight is a critical modifiable factor:

• Development of type 2 diabetes is 18% higher per unit of BMI increase from prepregnancy BMI at follow-up 1, 2
• The percentage developing T2DM is 18% higher per unit BMI at follow-up 3
• Interpregnancy weight gain is associated with increased risk of adverse pregnancy outcomes and higher risk of progression to type 2 diabetes 1

Ethnicity significantly affects risk:

• Development is 57% lower in White European populations compared to other ethnic groups (adjusted for ethnicity and follow-up) 3
• High-risk ethnicities include Arab, South/Southeast Asian, Latin American, Native American, African American, and Pacific Islander populations 6

Time Course of Risk

• The absolute risk increases linearly throughout a woman's lifetime 1, 2
• Risk remains elevated for more than 35 years after an affected pregnancy 5
• The age-specific hazard ratio shows an estimated 24% reduction per decade after an affected pregnancy, but risk never returns to baseline 5
• The hazard ratio is 3.87 (95% CI 2.60-5.75) at 6-15 years after an affected pregnancy 5

Prevention Strategies That Work

Both lifestyle intervention and metformin are highly effective:

• Only 5-6 individuals with prediabetes and history of GDM need to be treated with either intervention to prevent one case of diabetes over 3 years 1, 2, 7
• Lifestyle intervention reduced progression to diabetes by 35% over 10 years compared with placebo 1, 2, 7
• Metformin reduced progression to diabetes by 40% over 10 years compared with placebo 1, 2, 7

Healthy eating patterns significantly lower risk:

• Women who followed healthy eating patterns after GDM had significantly lower subsequent diabetes risk 1, 7
• Adjusting for BMI only moderately attenuated this association, indicating diet has independent protective effects 1

Breastfeeding provides metabolic benefits:

• Breastfeeding reduces the risk of developing type 2 diabetes in mothers with previous GDM 2, 7

Recommended Screening Schedule

Initial postpartum screening:

• Test for persistent diabetes or prediabetes at 4-12 weeks postpartum using a 75-g oral glucose tolerance test (OGTT) with nonpregnancy criteria 1, 2, 7
• OGTT is preferred over A1C at this timepoint because A1C may be persistently lowered by increased red blood cell turnover related to pregnancy, blood loss at delivery, or the preceding 3-month glucose profile 1

Lifelong surveillance is mandatory:

• Continue screening every 1-3 years thereafter, even if initial postpartum results are normal 1, 2, 7
• Acceptable screening methods include annual A1C, annual fasting plasma glucose, or triennial 75-g OGTT using nonpregnant thresholds 1, 2, 7
• Women recalling a history of GDM should be screened regularly for type 2 diabetes, even late in life 5

Clinical Pitfalls to Avoid

Poor communication between providers is a major barrier:

• Fewer than half (45.8%) of women with GDM by glucose tolerance test criteria had that history documented on their electronic problem list 8
• Obstetric providers and primary care providers often fail to communicate about GDM history, leading to missed screening opportunities 8
• Primary care providers are far more likely to order glucose screening when they know about GDM history (OR 4.31,95% CI 2.01 to 9.26), but they are less likely to ask about it (OR 0.43,95% CI 0.20 to 0.90) 8

Ensure GDM history is prominently documented in the electronic medical record problem list and communicated directly to the patient's primary care provider 8