The investigators believe that the pharmacological properties of Envarsus®, well studied in kidney transplantation, may be also suitable after simultaneous kidney and pancreas transplantation than Prograf. Indeed, Envarsus® has demonstrated a clinical efficacy and safety in a complete clinical development plan.

This study is to establish the pharmacokinetic profile of tacrolimus prolonged-release (hereafter referred to as 'ENVARSUS®') in diabetics who have undergone kidney and pancreas transplantation, and compare it to the pharmacokinetic profile of standard twice-daily tacrolimus. The study will be conducted in 25 patients hospitalized at Nantes University Hospital.

The study will be conducted in 25 patients hospitalized at Nantes University Hospital. Tacrolimus will be started on the day of surgery (or on the day after) according to Nantes local standard doses and practices. After a stable trough level is achieved (on postoperative day 7-17) the first PK profile will be measured. Subsequently, the switch to ENVARSUS® will be performed (initial dose of 0.17 mg/kg/day) on a single morning oral dosage regimen. A second PK profile will be measured, between 7 to 14 days after initiation of ENVARSUS®. All these PK measurements will take place during the post-operative recovery in the hospital (typically 2-3 weeks). All patients will receive Thymoglobulin or Alemtuzumab induction, Myfortic or Cellcept (or generics), with or without prednisone according to local practices. Anti-infectious prophylaxis will be given according to Nantes local practices.

Inclusion Criteria:

• Patient is willing and able to give informed consent for participation in the trial.
• Male or Female, aged 18 years or above.
• Type I Diabetics patients with end stage chronic renal failure
• Recipient of kidney and pancreas-transplant
• At least one of the two transplants are functioning at time of PK profile measurements : a patient with early pancreatic graft failure due to thrombosis may be included if the kidney is well functioning
• Standard immunosuppressive therapy has been started post-operatively, in accordance with local policy, including tacrolimus.
• In the Investigator's opinion, is able and willing to comply with all trial requirements.
• Patients with social security.

Exclusion Criteria:

The participant may not enter the trial if ANY of the following apply:

• Patient is inappropriate for standard immunosuppressive therapy.
• Any other significant disease or disorder which, in the opinion of the Investigator, may either put the patients at risk because of participation in the trial, or may influence the result of the trial, or the patient's ability to participate in the trial.
• Concomitant therapy with drugs potentially interfering with tacrolimus pharmacokinetics, especially those interfering with CYP3A4 (see 4.4 section in tacrolimus / ENVARSUS® summary of product characteristics).
• Loss of the pancreatic graft due to immunological causes
• Pregnant or breast-feeding women and female patient with potential childbearing refusing contraception.
• Vulnerable people: persons deprived of liberty; under trusteeship or under curatorship.