Serum uric acid level is associated with metabolic syndrome and microalbuminuria in Korean patients with type 2 diabetes mellitus

Abstract

Aims

To determine the relationship between serum uric acid, metabolic syndrome (MetS), and albuminuria in type 2 diabetic patients.

Methods

A total of 504 Korean patients with type 2 diabetes aged 57.3 years were retrospectively evaluated for clinical histories, anthropometric measurements, and biochemical studies. Urinary albumin excretion (UAE) was measured by a 24-h urine collection.

Results

Prevalence of MetS increased according to the quartiles of uric acid levels (≤3.7, 3.8 to 4.5, 4.6 to 5.5, and >5.5 mg/dl; 52.1%, 52.1%, 57.5%, and 71.6%, respectively, P<.001). Individual components of MetS (abdominal obesity, hypertriglyceridemia, low HDL-cholesterol, high blood pressure) were also significantly associated with the highest quintile of uric acid levels. Serum uric acid levels had significantly increased risk of albuminuria [odds ratio (OR) 1.425, 95% confidence interval (CI) 1.085-1.873] after adjusting for age, gender, and conventional risk factors. Uric acid level remains a significant predictor for abnormal albuminuria after adjusting for MetS presence as well as the use of angiotensin-converting enzyme inhibitor (ACEI) or angiotensin II receptor blocker (ARB) (OR 1.414, 95% CI 1.071-1.868).

Conclusion

An elevated uric acid level was significantly associated with MetS and was an independent predictor of albuminuria after adjusting for conventional risk factors and MetS. Regular measurements of uric acid level could give information for predicting the presence of MetS and albuminuria in Korean type 2 diabetic patients.

Introduction

Microalbuminuria is a well-known predictor of chronic kidney disease (Mogensen et al., 1985), cardiovascular disease (CVD), and mortality (Borch-Johnsen and Feldt-Rasmussen, 1999, Dinneen and Gerstein, 1997, Rossing and Hougaard, 1996) in patients with type 2 diabetes. Early detection and timely management of patients with microalbuminuria have been stressed for preventing disease progression. The recommendation for reducing albuminuria is to correct related risk factors including obesity, hypertension, diabetes, dyslipidemia, and smoking (Ravid and Brosh, 1998, Retnakaran and Cull, 2006). However, even if such a multifactorial management is successfully achieved, it frequently fails to lower urinary albumin excretion (UAE) and therefore there is a continuous need of finding novel risk factors for the microalbuminuria in patients with type 2 diabetes mellitus (T2DM).

Another proposed risk factor for albuminuria is metabolic syndrome (MetS), a cluster of risk factors for CVD (Bianchi and Penno, 2008, Chen and Muntner, 2004), although there is a controversy as some studies showed lack of association between microalbuminuria with insulin resistance (Hodge and Dowse, 1996, Zavaroni and Bonini, 1996). On the other hand, few reports have presented the association of uric acid levels with diabetic nephropathy and several experimental studies even suggested that hyperuricemia itself could be a causal factor for renal impairment (Johnson and Kang, 2003, Kanellis and Kang, 2005, Mercuro and Vitale, 2004, Perlstein and Gumieniak, 2004), despite the previous general concept considering uric acid as an innocent bystander.

Recently, there has been growing evidence as to the association between increased uric acid, MetS, and microalbuminuria (Fu and Wu, 2009, Fukui and Tanaka, 2008, Tseng, 2005). Despite prospective clinical cohorts as well as several experimental studies that suggest uric acid could predict the development of vascular-related diseases like hypertension, diabetes, and MetS (Feig et al., 2008), the association of uric acid levels in MetS and microalbuminuria is still unclear.

The purpose of this study was to investigate whether uric acid levels are significantly associated with MetS and UAE rates in Korean type 2 diabetic patients.