BACKGROUND: Combination fitness regimens (including aerobic and resistance exercises) are effective for improving cardio-respiratory fitness, reducing visceral fat and increasing insulin sensitivity in diabetic patients. The combination exercise intensity that a patient is capable of is limited by his or her aerobic capacity and one repetition maximum (1RM). We investigated the relationships between 1RM, aerobic exercise capacity and body mass index in patients with type 2 diabetes. METHODS: A total of 177 (men: 85, women: 92) diabetic subjects with HbA1c < or = 10% were enrolled. Muscle strength and 1RM were assessed bychest press (upper body) and leg press (lower body). We assessed aerobic capacity by VO2max and muscle mass by bioimpedance analysis. RESULTS: There was no correlation between 1RM and VO2max in type 2 diabetic patients (upper: P = 0.122, lower: P = 0.138 for men, and upper: P = 0.952, lower: P = 0.570 for women). However, 1RM was significantly correlated with muscle mass both in men and women (upper: r = 0.493, P < 0.001, r = 0.315, P = 0.002 lower: r = 0.437 P < 0.001, r = 0.307, P =0.003, respectively). There was also a significant correlation between 1RM and BMI. In obese male subjects with BMI > or = 25 kg/m2, we observed a significant correlation between muscle mass and BMI (r = 0.374, P = 0.032), but this correlation was not observed in women. CONCLUSION: Clinicians treating Korean type 2 diabetic subjects should recommend resistance exercise to their patients. In particular, obese women with diabetes may receive greater benefits by increasing muscle mass through resistance exercises.