['To analyze the effects of a long-term intensive lifestyle intervention including high-intensity interval training (HIIT) and Mediterranean diet (MedD) counseling on glycemic control parameters, insulin resistance and β-cell function in obese subjects.', 'The glycemic control parameters (fasting plasma glucose, glycated hemoglobin), insulin resistance, and β-cell function of 72 obese subjects (54 women; mean age\xa0=\xa053\xa0±\xa09\xa0years) were assessed at baseline and upon completion of a 9-month intensive lifestyle intervention program conducted at the cardiovascular prevention and rehabilitation center of the Montreal Heart Institute, from 2009 to 2012. The program included 2-3 weekly supervised exercise training sessions (HIIT and resistance exercise), combined to MedD counseling.', 'Fasting plasma glucose (FPG) (mmol/L) (before: 5.5\xa0±\xa00.9; after: 5.2\xa0±\xa00.6; P\xa0<\xa00.0001), fasting insulin (pmol/L) (before: 98\xa0±\xa057; after: 82\xa0±\xa043; P\xa0=\xa00.003), and insulin resistance, as assessed by the HOMA-IR score (before: 3.6\xa0±\xa02.5; after: 2.8\xa0±\xa01.6; P\xa0=\xa00.0008) significantly improved, but not HbA1c (%) (before: 5.72\xa0±\xa00.55; after: 5.69\xa0±\xa00.39; P\xa0=\xa00.448), nor β-cell function (HOMA-β, %) (before: 149\xa0±\xa078; after: 144\xa0±\xa075; P\xa0=\xa00.58).'] Does intensive lifestyle intervention including high-intensity interval training program improve insulin resistance and fasting plasma glucose in obese patients?