How to start Oral Hypoglycemic Agents (OHAs) postpartum in a woman with a history of gestational diabetes or pre-existing diabetes?

Starting Oral Hypoglycemic Agents (OHAs) Postpartum

Immediate Postpartum Management by Diabetes Type

For women with gestational diabetes (GDM), stop all insulin immediately after delivery and do not start oral hypoglycemic agents in the immediate postpartum period. 1

Gestational Diabetes Mellitus (GDM)

• Discontinue insulin completely at delivery 1
• Monitor blood glucose before meals and 2 hours postprandially for 48 hours 1
• Do not initiate oral hypoglycemic agents unless fasting blood glucose exceeds 126 mg/dL (7 mmol/L) or postprandial values exceed 200 mg/dL (11 mmol/L) during the 48-hour monitoring period 1
• If hyperglycemia persists beyond 48 hours, consult with a diabetologist before starting any medication 1

Type 2 Diabetes (Pre-existing, Insulin-Treated During Pregnancy)

• Continue insulin at half the pregnancy dose immediately postpartum while awaiting diabetologist consultation 1
• Insulin sensitivity increases dramatically with placental delivery, with requirements dropping to approximately 34% lower than prepregnancy levels 1
• Oral hypoglycemic agents can be restarted in Type 2 diabetes patients who were on them preconception, but only if NOT breastfeeding 1
• If breastfeeding, continue insulin therapy as oral agents have limited safety data during lactation 1

Type 1 Diabetes

• Never stop basal insulin - risk of diabetic ketoacidosis is significant 1
• Resume basal-bolus insulin scheme at either 80% of prepregnancy doses OR 50% of end-of-pregnancy doses 1
• If patient was on insulin pump, restart immediately when IV insulin is discontinued 1
• Oral hypoglycemic agents are not appropriate for Type 1 diabetes 1

Postpartum Testing and Long-Term Management

Testing Timeline for GDM

• Perform 75-g oral glucose tolerance test (OGTT) at 4-12 weeks postpartum using non-pregnancy diagnostic criteria 1
• OGTT is preferred over A1C because A1C may be falsely lowered by increased red blood cell turnover during pregnancy and blood loss at delivery 1
• If both fasting glucose ≥126 mg/dL AND 2-hour glucose ≥200 mg/dL are abnormal, diabetes is diagnosed 1
• If only one value is abnormal, repeat testing to confirm 1

When to Start OHAs After GDM

If postpartum OGTT reveals Type 2 diabetes or prediabetes:

• For Type 2 diabetes diagnosis (fasting ≥126 mg/dL or 2-hour ≥200 mg/dL): Start metformin or other oral agents per standard diabetes treatment guidelines 1
• For prediabetes (impaired fasting glucose or impaired glucose tolerance): Consider metformin for diabetes prevention, as only 5-6 women with GDM history and prediabetes need treatment to prevent one case of diabetes over 3 years 1

If postpartum OGTT is normal:

• Do not start oral hypoglycemic agents 1
• Retest every 1-3 years, as 50-70% of women with GDM history will develop Type 2 diabetes within 15-25 years 1
• Women with GDM have a 10-fold increased risk of Type 2 diabetes compared to women without GDM 1

Breastfeeding Considerations

• All women with diabetes should be supported in breastfeeding due to nutritional, immunological, and long-term metabolic benefits 1
• Insulin is safe during breastfeeding and remains the preferred agent 1
• Lactation increases risk of overnight hypoglycemia, requiring insulin dose adjustments 1
• Oral hypoglycemic agents have limited safety data during breastfeeding - metformin and glyburide appear compatible but insulin remains preferred 2

Critical Pitfalls to Avoid

• Never continue insulin at pregnancy doses - this will cause severe hypoglycemia due to dramatic increase in insulin sensitivity postpartum 1
• Never stop basal insulin in Type 1 diabetes - even briefly, as diabetic ketoacidosis can develop rapidly 1
• Never start oral agents in the immediate postpartum period for GDM - wait for 4-12 week OGTT results to determine if diabetes persists 1
• Never use A1C alone for postpartum diabetes screening - it is unreliable due to pregnancy-related changes in red blood cell turnover 1
• Do not assume normal glucose tolerance after GDM - lifetime screening is essential given the 50-70% risk of eventual diabetes 1

Contraception Planning

• Discuss and implement contraception immediately postpartum for all women with diabetes of reproductive potential 1
• Long-acting reversible contraception may be ideal 1
• This is critical because most pregnancies are unplanned, and preconception glycemic control is essential to prevent congenital malformations in future pregnancies 1