Metformin Versus Insulin in Gestational Diabetes

Gestational diabetes is traditionally treated with insulin. Metformin is a peroral drug used worldwide in the treatment of type 2 diabetes and also in a few studies on patients with gestational diabetes. The investigators aim is to compare insulin and metformin in the treatment of gestational diabetes. The investigators hypothesis is that there is no difference between insulin and metformin treated mothers in the main outcome criteria (birth weight, neonatal complications).

Gestational diabetes is traditionally treated with insulin. Metformin is a peroral drug used worldwide in the treatment of type 2 diabetes and also in a few studies on patients with gestational diabetes. The investigators aim is to compare insulin and metformin in the treatment of gestational diabetes. The investigators hypothesis is that there is no difference between insulin and metformin treated mothers in the main outcome criteria (birth weight, neonatal complications). The study was performed as a randomized controlled trial in one center, Turku University hospital using the non-inferiority design in June 2006 - December 2010. The final study population consisted of altogether 217 women, of whom 110 received metformin and 107 insulin.

NPH insulin once or twice daily and/or insulin lispro or aspart according to preprandial and postprandial glucose values

subcutaneous Neutral Protamine Hagedorn (NPH) insulin and/or rapid acting insulin analog adjusted according to plasma glucose values until delivery

birth weight adjusted for gestational weeks expressed as standard deviation units using data from Finnish fetal growth charts in normal pregnancies

Participants with pregnancy induced hypertension defined as blood pressure over 140/90 mmHg or increase in systolic blood pressure > 30 mmHg or diastolic blood pressure > 15 mmHg

Apgar score 0-10. 0-2 points from heart rate; 0-2 points for respiratory effort; 0-2 points for skin colour; 0-2 points for muscle tone; 0-2 points for reflex response. For all items the higher the value, the better the outcome

Inclusion Criteria: Mothers with gestational diabetes who had at least twice plasma glucose at fasting > 5.4 mmol/L and/or 1 hour postprandial value > 7.7 mmol/L at 24 to 32 gestational weeks Exclusion Criteria: Fasting glucose > 7.0 mmol/L or 1 hour postprandial plasma glucose > 11.0 mmol/L or Glycosylated hemoglobin A1c (HbA1c) > 7.0% Renal, hepatic or cardiac failure Pregestational use of metformin Pregnancy with multiple fetuses

Huhtala MS, Ronnemaa T, Pellonpera O, Tertti K. Cord serum metabolome and birth weight in patients with gestational diabetes treated with metformin, insulin, or diet alone. BMJ Open Diabetes Res Care. 2021 May;9(1):e002022. doi: 10.1136/bmjdrc-2020-002022.

Huhtala MS, Tertti K, Juhila J, Sorsa T, Ronnemaa T. Metformin and insulin treatment of gestational diabetes: effects on inflammatory markers and IGF-binding protein-1 - secondary analysis of a randomized controlled trial. BMC Pregnancy Childbirth. 2020 Jul 11;20(1):401. doi: 10.1186/s12884-020-03077-6.

Huhtala MS, Tertti K, Pellonpera O, Ronnemaa T. Amino acid profile in women with gestational diabetes mellitus treated with metformin or insulin. Diabetes Res Clin Pract. 2018 Dec;146:8-17. doi: 10.1016/j.diabres.2018.09.014. Epub 2018 Sep 15.

Pellonpera O, Ronnemaa T, Ekblad U, Vahlberg T, Tertti K. The effects of metformin treatment of gestational diabetes on maternal weight and glucose tolerance postpartum--a prospective follow-up study. Acta Obstet Gynecol Scand. 2016 Jan;95(1):79-87. doi: 10.1111/aogs.12788. Epub 2015 Nov 8.

Tertti K, Laine K, Ekblad U, Rinne V, Ronnemaa T. The degree of fetal metformin exposure does not influence fetal outcome in gestational diabetes mellitus. Acta Diabetol. 2014 Oct;51(5):731-8. doi: 10.1007/s00592-014-0570-6. Epub 2014 Mar 16.