Metformin Use to Improve Pregnancy Outcome in Women With Type 1 Diabetes.

Insulin resistance during pregnancy of diabetes mellitus type 1 patients (DM1) increases the need for insulin and makes it more difficult to maintain normoglycemia. Fetal exposure to hyperglycemia induces macrosomia which increases fetal and neonatal morbidity and mortality. Further more obesity and excess weight gain during pregnancy enhances insulin resistance and it's an independent risk factor for fetal macrosomia.

Metformin is a medical treatment for type 2 diabetes (DM2) where consequential pathophysiology includes insulin resistance. It reduces hepatic glucose production and enhances the use of glucose in muscles relieving insulin resistance. Metformin has also found to inhibit weight gain effectively.

Metformin has approved to be safe and effective in patients with gestational diabetes (GDM). It has found to reduce weight gain and improve postprandial blood glucose levels during pregnancy and reduce neonatal birth trauma in GDM. However, there are no previous studies about the use of metformin in pregnant women with DM1.

Two hundred women with DM1 will be randomized to get placebo or metformin in addition to regular insulin treatment. The sample size has been estimated to demonstrate the difference of 15 % in the need to increase insulin dosages during the pregnancy between the study groups.

Inclusion criteria

• a pregnancy of a woman with type 1 diabetes.

Exclusion criteria

• multiple pregnancy, significant underlying disease (hearth disease, kidney transplant, IBD (inflammatory bowel disease ), SLE (systemic lupus erythematosus ), diseases with use of high dosage corticosteroids (severe asthma or rheumatic disease), severe complications of diabetes (nephropathy, neuropathy, gastroparesis or severe retinopathy), substance abuse, smoking, BMI <18, strong early pregnancy nausea (=hyperemesis)