A single center, double-blind, placebo-controlled, randomized, crossover, phase II study to assess the effect of aleglitazar on cardiac energetics and function in patients with uncomplicated type 2 diabetes mellitus and no history of coronary artery disease who are drug-naïve or treated with stable metformin. Eligible patients will receive either 150 mcg aleglitazar or placebo orally daily for 6 weeks. After a washout period of 6 weeks, patients will cross over to the treatment not yet received.

Inclusion Criteria:

• Adult patients, 40 to 70 years of age (inclusive) at screening
• Patients with Type 2 diabetes mellitus diagnosed at least 12 weeks before screening and either drug-naïve or treated with stable metformin monotherapy for at least 12 weeks prior to screening
• HbA1c >/= 7 % and \