BACKGROUND AND PURPOSE:

• While some recent GDM studies have shown that metformin can achieve comparable pregnancy outcomes vs insulin, not all clinical guidelines currently endorse the use of metformin in this setting
• Picón-César et al. (AJOG, 2021) compared metformin vs insulin in women with GDM who did not achieve glycemic control with lifestyle changes alone

METHODS:

• Multicenter, open-label, parallel arms, randomized clinical trial
• Participants
  • Women with GDM
  • 18 to 45 years
  • Second or third trimesters of pregnancy
• Interventions
  • Metformin
  • Insulin (Detemir and/or Aspart)
• GDM screening
  • Selective screening in first and third trimester
  • Universal screening at 24 to 28th gestational weeks: 50g oral glucose tolerance (O’Sullivan test) screening
  • Positive screen at 24 to 28 weeks followed by 100g OGTT diagnostic test        
• Study design
  • Analysis based on intention to treat
• Power analysis
  • Non-inferiority margin of 25%
  • Power 80% | Alpha error 0.05
  • Sample size: Total 231 (82 patients per group)
• Primary outcomes
  • Glycemic control (mean glycemia, pre-prandial and postprandial) and hypoglycemic episodes
  • Obstetric and perinatal results and complications
    • Hypertensive disorders | Sort of labor | Prematurity | Macrosomia | LGA | NICU stay | RDS | Hypoglycemia | Jaundice

RESULTS:

• 100 women in insulin group | 100 women in metformin group
• Mean fasting and postprandial glycemia did not differ between groups
• Postprandial glycemia was significantly better after lunch and/or dinner in the metformin group
• Hypoglycemic episodes were significantly more common in the insulin group
  • Insulin: 55.9%
  • Metformin: 17.7%
  • OR 6.118 (95% CI, 3.134 to 11.944; P=0.000)
• Women who received metformin gained less weight in between the enrollment and the pre-partum visit (36 to 37 weeks)
  • Insulin: 3.87±3.50 Kg
  • Metformin: 1.35±3.21 Kg
  • P=0.000
• The metformin group also experienced significantly fewer
  • Labor inductions
    • Insulin: 62.5%
    • Metformin: 45.7%
    • OR 0.506 (95% CI, 0.283 to 0.903; P=0.029)
  • Cesarean deliveries
    • Insulin: 52.6%
    • Metformin: 27.6%
    • OR 0.345 (95% CI, 0.187 to 0.625; P=0.001)
• There were no differences between the groups for the following
  • Mean birth weight
  • Macrosomia and LGA
  • Neonatal complications
• The lower cesarean delivery rate for women treated with metformin was not associated with
  • Macrosomia
  • LGA or SGA
  • Any other complications of pregnancy

CONCLUSION:

• Compared with insulin, treatment of GDM with metformin led to
  • Better glycemic control after meals
  • Lower risk of hypoglycemic episodes
  • Less maternal weight gain
• Women in both groups had mostly similar obstetric and perinatal outcomes

Learn More – Primary Sources:

MeDiGes Study. Metformin versus insulin in gestational diabetes: Glycemic control, and obstetrical and perinatal outcomes. Randomized prospective trial.

Related ObG Topics:

ACOG and SMFM Both Release Guidance on Gestational Diabetes – Insulin vs Metformin for First-Line Therapy?

MiTy RCT Results: Is Metformin Use in Pregnancy Associated with Better Maternal and Neonatal Outcomes?

Metformin in Pregnancy

Metformin vs. Insulin for GDM: How Do Neonatal and Childhood Growth Rates Compare?

The MiG-TOFU Study: Gestational Diabetes, Metformin and Metabolic Outcomes in Offspring 7 Years Later