title: Metformin vs. insulin in gestational diabetes. A randomized study characterizing metformin patients needing additional insulin.
abstract: OBJECTIVE
  We compared metformin with insulin as treatment of gestational diabetes mellitus (GDM). Furthermore, we aimed to characterize metformin-treated patients needing additional insulin to achieve prespecified glucose targets.
  
  
  METHODS
  We conducted a single centre randomized controlled study with non-inferiority design comparing metformin and insulin in the treatment of 217 GDM patients having birth weight as primary outcome variable.
  
  
  RESULTS
  There were no significant differences in mean birth weight expressed in grams [+15 (90% confidence interval (CI): -121 to 89)] or SD units [+0.04 (90% CI: -0.27 to 0.18)] between the metformin and insulin groups. There were no significant differences in neonatal or maternal data between the groups. Only 23 (20.9%) of the 110 patients in the metformin group needed additional insulin. Compared with the patients on metformin only, those needing additional insulin were older (p = 0.04), their oral glucose tolerance test had been performed earlier and diabetes therapy started earlier in gestation (p = 0.01 and p = 0.004, respectively). The risk for additional insulin was 4.6-fold in women with baseline serum fructosamine concentration above median compared with those below median.
  
  
  CONCLUSIONS
  Metformin is an effective alternative to insulin in the treatment of GDM patients. Serum fructosamine may help in predicting the adequacy of metformin treatment alone.
authors.affiliation: Department of Obstetrics and Gynecology, Turku University Hospital, Turku, Finland. kristiina.tertti@tyks.fi
authors.forename: K
authors.initials: K
authors.lastname: Tertti
authors.forename: U
authors.initials: U
authors.lastname: Ekblad
authors.forename: P
authors.initials: P
authors.lastname: Koskinen
authors.forename: T
authors.initials: T
authors.lastname: Vahlberg
authors.forename: T
authors.initials: T
authors.lastname: Rönnemaa
mesh_terms: D000328:Adult; D001724:Birth Weight; D001786:Blood Glucose / Q000187:drug effects* / Q000378:metabolism; D016640:Diabetes, Gestational / Q000097:blood / Q000188:drug therapy*; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000097:blood / Q000627:therapeutic use*; D007328:Insulin / Q000097:blood / Q000627:therapeutic use*; D008297:Male; D008687:Metformin / Q000097:blood / Q000627:therapeutic use*; D011247:Pregnancy; D011256:Pregnancy Outcome; D016896:Treatment Outcome
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D008687:Metformin