Inclusion Criteria:

• Diagnosis of type 2 diabetes mellitus for at least 5 years;
• Treatment with oral antidiabetic drugs in fixed combination (Combo, i.e. glibenclamide 2.5 mg + metformin 400 mg, 2 or 3 tablets, at stable dose in the last 3 months);
• HbA1c >= 8% and <= 11%;
• Body mass index (BMI) > 27 and < 35 kg/m2;
• Willingness and demonstrated ability to inject insulin;
• Demonstrated ability and willingness to perform self-monitoring of blood glucose (SMBG);

Exclusion criteria:

• Patients diagnosed with type 1 insulin dependent diabetes;
• Patients with latent autoimmune diabetes of adults (LADA), defined as fasting C-peptide levels < 1 ng/ml;
• Cardiac status NYHA III-IV;
• Impaired renal function as shown by (but not limited to) serum creatinine >= 1.5 mg/dl for males or >= 1.4 mg/dl for females;
• Planned pregnancy, pregnant or lactating females;
• Failure to use adequate contraception (women of current reproductive potential only);
• Any current malignancy, previous breast cancer, or malignant melanoma within the past 5 years;
• Diagnosis of dementia
• Hypersensitivity to insulin or any of their components or to metformin;
• Current or previous insulin therapy other than during hospitalisations;
• Inability or unwillingness to continue metformin at study dosages throughout the study;
• Treatment with intermittent doses of systemic steroids or large doses of inhaled steroids for the past one year (fixed doses for the past 6 months is acceptable providing there is no plan to change the dosage regime);
• Stroke, Myocardial Infarction (MI), Coronary Artery Bypass Graft (CABG), Percutaneous Transluminal Coronary Angioplasty (PTCA), or Angina Pectoris within the last 12 months;
• History of drug or alcohol abuse;
• Receipt of an experimental drug or use of an experimental device within the 30 days prior to study entry;