Relationship between insulin resistance and inflammatory markers and anti-inflammatory effect of losartan in patients with type 2 diabetes and hypertension.

Background: It is now well established that vascular inflammation and endothelial dysfunction associated with cardiovascular diseases contributes to insulin resistance.

Methods: We investigated the relationship between the homeostasis model assessment-insulin resistance index (HOMA-R) and various serum inflammatory markers and the effect of losartan on serum concentrations of these markers in patients with type 2 diabetes and hypertension. The patients were divided into 2 groups according to the value of HOMA-R with 60 patients with values=2.4 in Group A and 44 patients with values>2.5 in Group B. The variables were measured at baseline and after 6 months of treatment with losartan (50 mg/day).

Results: The HOMA-R concentrations were positively related to TNF-alpha (r=0.336, P<0.01) and inversely related to adiponectin (r=-0.405, P<0.01) and extracellular-superoxide dismutase (EC-SOD) (r=-0.452, P<0.01). Stepwise multiple regression analysis showed a significant relationship between HOMA-R and adiponectin (F=8.74) and EC-SOD (F=14.39). In Group B, losartan treatment significantly increased the serum concentrations of EC-SOD and adiponectin and decreased TNF-alpha and HOMA-R.

Conclusion: Serum EC-SOD concentrations may be a sensitive biochemical marker of insulin resistance in patients with type 2 diabetes and hypertension and that losartan improves insulin sensitivity by increasing EC-SOD and adiponectin production and decreasing TNF-alpha production.