Metformin use in an obese diabetic patient from weeks 1 to 21 of pregnancy.

: A 43-year-old diabetic woman was admitted in the 15th week of her first pregnancy. When HbA1c levels were 8.2%, we began diet therapy and continuous subcutaneous insulin infusion (CSII) therapy. The HbA1c levels subsequently ranged from 6.2 to 6.7%. She was delivered without complications of a healthy male infant (3120g) in the 38th week. Metformin was then administered. Six months later she was diagnosed as being in the 21st week of pregnancy. We changed from metformin to CSII therapy immediately. The HbA1c levels had ranged from 6.0 to 6.4% before the CSII therapy and from 5.8 to 6.6% after the CSII therapy during the entire second pregnancy. A macrosomia delivery (4070g) occurred in the 37th week. Although glycemic control was better during the 2nd pregnancy than the 1st pregnancy, metformin use until the 21st week may have induced macrosomia.