To examine the effect of muscle strength on insulin resistance, we investigated the association between quantitative lower-extremity muscle strength and insulin resistance index as evaluated by homeostasis model assessment (HOMA-IR) in patients with type 2 diabetes (20 men and 20 women, mean age ± SD: 53.3 ± 12.7 years). By simple linear regression analyses, the knee extension force normalized for body weight (%KEF) was found to be significantly correlated with HOMA-IR in both male (r = −0.510, P < 0.05) and female patients (r = −0.462, P < 0.05). Stepwise regression analysis also showed that %KEF was an independent determinant of HOMA-IR (β = −0.331, F = 5.400, P < 0.005), as was BMI (β = 0.409, F = 8.260, P < 0.05). Our data suggest that lower-extremity muscle strength is independently associated with insulin resistance, which seems to be consistent with previous reports that resistance training improves glycemic control in type 2 diabetic patients. Further studies based on a larger study population will be required to confirm this possibility.