Sample size: based on a previous study by "Pallayova" et al. in patients having type 2 diabetes, investigators anticipate a difference between groups of 1.3 (SD 2.07) for the mean nocturnal glycemia. For a alpha threshold of 5% and a study power of 80%, the study should include 32 patients in each group. Taking in account a possible 25% of dropout the study will need to include 40 patients by randomized arm to demonstrate an effect.