The study is to treat metformin dose-escalation diabetic subjects of all stages of renal failure (stages 1-5) and compare their rates of erythrocyte metformin (best reflections of a possible accumulation than those of plasma) to the therapeutic range. A number of 12 patients by stage is considered, 60 patients in total.

Inclusion Criteria:

• Diabetic patients not treated with metformin, no treatment diabetic or have been treated but poorly balanced (HbA1c> 7%) and an applicant building with metformin; at any stage renal stable (stages 1-5 according to the classification MDRD)
• Patients aged 18 to 80 years;
• Patients with an assessment of renal function dating back more than 3 months;
• Patients whose renal function is stable, on the criterion of the absence of fluctuation over 30% of renal function of creatinine clearance in the last three months, a reference to renal function at least 3 months from the balance sheet inclusion is necessary.

Exclusion Criteria:

• Patient over 80 years
• Patients incapacitated adults (protected under guardianship)
• No previous reference creatinine;
• Fluctuation over 30% of renal function (creatinine clearance) in the three months;
• Reduction in BMI of more than 5% during the last 3 months;
• Severe hepatic impairment (Child stage> A);
• No reference to liver stages 3-5
• Patients to be an X-ray with injection of contrast.