Elevated Fasting Insulin Level Significantly Increases the Risk of Microalbuminuria

Background: Microalbuminuria is significantly associated with long-term prognosis in the general population as well as in diabetic patients. It is well known that insulin resistance (IR) can induce microalbuminuria, but an elevated fasting insulin level, which is an early clinical manifestation of IR, as a risk factor for microalbuminuria has not been clarified, so we investigated the association between fasting insulin level and the development of microalbuminuria in a general population. Methods and Results: A total of 1,192 non-diabetic Korean men without microalbuminuria in 2005 were followed until 2010. They were categorized into 3 groups according to their fasting insulin levels and monitored for the development of microalbuminuria. The incidence of microalbuminuria was compared among groups, and Cox proportional hazards models were used to calculate the hazard ratios for microalbuminuria according to the fasting insulin levels. During 4,013.0 person-years of follow-up, 51 incident cases of microalbuminuria developed between 2006 and 2010. The incidence of microalbuminuria increased in proportion to the fasting insulin levels (tertile 1: 1.8%, tertile 2: 4.5%, tertile 3: 6.5%, P<0.001). Hazard ratios for microalbuminuria also increased in proportion to the fasting insulin levels [tertile 1: reference, tertile 2: 2.44 (1.01-5.89), tertile 3: 3.30 (1.40-7.78), respectively, P for trend 0.013]. Conclusions: Elevated fasting insulin level was associated with the future development of microalbuminuria.