['To determine whether increased daily physical activity improves mitochondrial function and/or lipid oxidation in type 2 diabetes.', 'Volunteers with (n = 10) and without (n = 10) type 2 diabetes were matched for habitual physical activity, age, sex, and weight. Basal and maximal mitochondrial activity, physical activity, and resting substrate oxidation were measured at baseline and after 2 and 8 weeks of increased physical activity.', 'Baseline physical activity (6,450 +/- 851 vs. 7,638 +/- 741 steps/day), basal ATP use (12 +/- 1 vs. 12 +/- 1 micromol x ml(-1) x min(-1)), phosphocreatine recovery from exercise (31 +/- 5 vs. 29 +/- 3 s), and basal lipid oxidation (0.57 +/- 0.07 vs. 0.65 +/- 0.06 mg x kg body wt(-1) x min(-1)) were similar in people with and without type 2 diabetes. There was a significant increase in physical activity after 8 weeks (12,322 +/- 1,979 vs. 9,187 +/- 1,159 steps/day, respectively). Following increased physical activity, there were no changes in basal ATP use or phosphocreatine recovery after exercise in either group. Basal lipid oxidation increased after 8 weeks of increased physical activity in people with type 2 diabetes (0.79 +/- 0.08 mg x kg(-1) x min(-1)) but not people without (0.68 +/- 0.13 mg x kg body wt(-1) x min(-1)).'] Does increased daily walking improve lipid oxidation without changes in mitochondrial function in type 2 diabetes?