Clinical experience of metformin in treating patients with hyperglycemia in pregnancy

Objective To evaluate the efficacy and safety of metformin in patients with hyperglycemia in pregnancy. Methods A total of 135 patients who were diagnosed with gestational diabetes mellitus (GDM), overt diabetes mellitus (ODM), or pre-gestational diabetes mellitus (PGDM) at the endocrinology outpatient clinic of Shengjing Hospital affiliated to China Medical University were recruited. Patients were divided into conventional treatment group (n=60, including those received insulin treatment only) and metformin group (n=75, including those received both insulin and metformin treatment). The differences between the two groups were compared using Student′s t-test or Mann-Whitney U test, and the differences between multiple groups were tested by ANOVA or Kruskal-Wallis H test. Categorical variables were compared using Chi-square test. Results Regardless of the type of hyperglycemia in pregnancy, there was no significant difference in weight gain during pregnancy between the groups. The increase of basal, mealtime and total insulin dosage in the metformin group of GDM and PGDM patients were significantly lower than those in the conventional treatment group [the increase of total insulin was 0.02 (0.00, 0.18) vs 0.07 (0.06, 0.37) U/kg and 0.41 (0.15, 0.92) vs 0.73 (0.36, 1.10) U/kg, respectively, Z=-6.829, -5.756, both P<0.05]. The increase of mealtime and total insulin dosage in ODM metformin group were also significantly lower compared with control group [the increase of total insulin dosage was 0.41 (0.24, 0.55) vs 0.51 (0.36, 0.98) U/kg, Z=-4.775, P<0.05]. In patients with insulin dosage greater than 100 U/d or patients with pre-gestational body mass index (BMI) greater or equal to 28 kg/m2, the increases of insulin dosage in the metformin group was also significantly lower than those in the conventional treatment group (Z=-6.866--5.080, all P<0.05). Conclusion Combination with metformin during pregnancy can reduce insulin dosage, especially for patients with high insulin dosage or obesity. Key words: Hyperglycemia, gestational; Metformin; Insulin