Could a common diabetes drug protect arteries in type 1 diabetes?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Type 1 diabetes 2. Women and Men ≥ 18 years old and ≤ 80 years old with: * Complications: diabetic retinopathy and/or nephropathy (with creatinine clearance ≥ 60 mL/mn) and/or neuropathy and/or peripheral arterial occlusive disease and/or cardiopathy and/or stroke and/or * cardiovascular risk factors : hypertension and/or dyslipidemia (HDL \< 0.35g/L or LDL \> 1.9g/L or treated dyslipidemia) and/or tobacco use (old or active smoking greater than 5 pack years) and/or * Diabetes duration \>20 years 3. For women in childbearing age, effective contraception during the whole trial 4. Signed written informed consent 5. Affiliation of a social security regime (AME excluded) Exclusion Criteria: 1. Creatinine clearance of less than 3 months \<60 mL/mn (MDRD) at the inclusion time 2. Known metformin contra-indication: severe liver insufficiency -CHILD B or C, heart failure (FEVG\<45%) or history of pulmonary edema, respiratory insufficiency with history of acute respiratory failure or patients receiving oxygen therapy, chronic ethylism, lactic acidosis 3. Know sensitivity to metformin or to any of its excipients or placebo excipients (lactose) 4. Indication or history of lower limb angioplasty (with stenting) and/or bypass 5. Previous treatment with metformin (within 3 months prior to inclusion) 6. HbA1c of less than 3 months \>11% 7. Chronic inflammatory disease or chronic immune-suppressive drugs intake 8. Participation in an another interventional trial (Jardé 1 and 2) or in the exclusion period of any other interventional study 9. Pregnancy woman (confirmed by a sanguine beta-human chorionic gonadotropin test) or breastfeeding woman 10. Patient under legal protection measure (tutorship or curatorship) or deprived of freedom 11. Unable to consent