title: The effects of metformin treatment of gestational diabetes on maternal weight and glucose tolerance postpartum--a prospective follow-up study.
abstract: BACKGROUND
  Metformin seems to reduce gestational weight gain compared with insulin in women with gestational diabetes (GDM). Women with GDM requiring insulin are more likely to develop abnormal glucose tolerance postpartum than women treated with diet only. In this prospective follow-up study of a randomized clinical trial, we investigated the effect of metformin treatment in women with GDM on weight gain and glucose tolerance postpartum.
  
  
  METHODS
  Women with GDM with two or more pathologic glucose values at 2-h 75-g oral glucose tolerance test (OGTT) were recruited. Those needing medication to achieve sufficient glycemic control were randomized at 22-34 weeks of gestation to either metformin (n = 110) or insulin (n = 107) treatment until delivery. A third GDM group (n = 128) requiring no medication had only diet treatment. Weight, OGTT and glycosylated hemoglobin (HbA1c) were determined at 6-8 weeks and 1 year postpartum.
  
  
  RESULTS
  At least one postpartum visit was attended by 104, 101 and 120 women in the metformin, insulin and diet-only groups, respectively. No significant differences were found in the change of weight, HbA1c or OGTT glucose values between the groups during the study (p ≥ 0.121 in all comparisons). One year postpartum the diet-only group had less impaired glucose tolerance compared with the metformin and insulin groups (7.1%, 19.1% and 15.6%, respectively; overall p = 0.039) and a lower incidence of diabetes (p = 0.027).
  
  
  CONCLUSIONS
  Short-term metformin therapy does not affect weight, HbA1c or OGTT glucose values postpartum compared with insulin or diet-only treatments. Women with GDM requiring no medication are least likely to develop impaired glucose tolerance or diabetes postpartum.
authors.affiliation: Department of Obstetrics and Gynecology, Turku University Hospital and University of Turku, Turku, Finland.
authors.forename: Outi
authors.identifier: http://orcid.org/0000-0001-9272-2278
authors.initials: O
authors.lastname: Pellonperä
authors.affiliation: Department of Medicine, Turku University Hospital and University of Turku, Turku, Finland.
authors.forename: Tapani
authors.identifier: http://orcid.org/0000-0001-7440-2828
authors.initials: T
authors.lastname: Rönnemaa
authors.affiliation: Department of Obstetrics and Gynecology, Turku University Hospital and University of Turku, Turku, Finland.
authors.forename: Ulla
authors.identifier: http://orcid.org/0000-0001-8669-0521
authors.initials: U
authors.lastname: Ekblad
authors.affiliation: Department of Biostatistics, University of Turku, Turku, Finland.
authors.forename: Tero
authors.identifier: http://orcid.org/0000-0002-4935-3056
authors.initials: T
authors.lastname: Vahlberg
authors.affiliation: Department of Obstetrics and Gynecology, Turku University Hospital and University of Turku, Turku, Finland.
authors.forename: Kristiina
authors.identifier: http://orcid.org/0000-0001-8950-3103
authors.initials: K
authors.lastname: Tertti
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects*; D016640:Diabetes, Gestational / Q000178:diet therapy / Q000188:drug therapy*; D005260:Female; D005500:Follow-Up Studies; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000187:drug effects; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D007328:Insulin / Q000494:pharmacology* / Q000627:therapeutic use; D008687:Metformin / Q000494:pharmacology* / Q000627:therapeutic use; D049590:Postpartum Period; D011247:Pregnancy; D011446:Prospective Studies; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; D007328:Insulin; D008687:Metformin; C517652:hemoglobin A1c protein, human
keywords: Gestational diabetes; glucose tolerance; insulin; metformin; postpartum; weight