Microalbuminuria is an indicator of an increased cardiovascular risk in diabetic and nondiabetic populations (1,2). Predominantly based on studies in type 2 diabetic populations, it has been suggested that microalbuminuria is an early indicator of atherosclerosis (3). Whether, in nondiabetic subjects, microalbuminuria is an independent indicator of subclinical atherosclerosis or merely a reflection of the increased prevalence of cardiovascular risk factors remains a matter of debate (4). Therefore, in the present study, we investigated the relation between urinary albumin excretion (UAE) and intima-media thickness (IMT) in both a nondiabetic and a type 2 diabetic population.
Subjects were recruited on the basis of reproducible microalbuminuria (UAE once >10 mg/l in an early morning spot urine and at least once 15–300 mg/24 h in 2 × 24 h urine samples). The IMT was measured at the posterior wall of the left common carotid artery using radio frequency signal analysis obtained by M-mode ultrasonography. Type 2 diabetes was defined as currently using antidiabetic drugs or a fasting plasma glucose exceeding 6.1 mmol/l. A total of 481 men and 257 women with a mean age of 50 years were included. Adjusted for age and sex, UAE was related to diastolic and systolic blood pressure as well as BMI in diabetic (n = 57) and nondiabetic subjects (n = 681). All relations between UAE and these variables were stronger in the type 2 diabetic population. In both diabetic and nondiabetic subjects, a positive relation was present between UAE and IMT (Table 1). In nondiabetic subjects, this relation could no longer be demonstrated after correction for age, sex, and classical cardiovascular risk indicators. In contrast, in type 2 diabetes patients, the relation between UAE and IMT remained highly significant after risk factor correction.
This study shows that UAE is strongly related to subclinical atherosclerosis (assessed as IMT) in type 2 diabetes patients, whereas in healthy volunteers, the relation between UAE and IMT is predominantly a consequence of a clustering of cardiovascular risk indicators. The latter observation implies that if microalbuminuria proves to be an independent risk indicator for cardiovascular disease in the nondiabetic population, this is due to mechanisms other than enhanced atherosclerosis progression per se.
Partial Spearman correlation coefficients of the relation between UAE and carotid IMT in type 2 diabetic and nondiabetic subjectslegend
| Carotid IMT (mm) . | UAE (mg/24 h) . | P . |
|---|---|---|
| Nondiabetic subjects (n = 681) | ||
| Model 1 | 0.14 | <0.001 |
| Model 2 | 0.04 | NS |
| Model 3 | −0.01 | NS |
| Type 2 diabetic subjects (n = 57) | ||
| Model 1 | 0.31 | 0.02 |
| Model 2 | 0.37 | 0.0056 |
| Model 3 | 0.40 | 0.0049 |
| Carotid IMT (mm) . | UAE (mg/24 h) . | P . |
|---|---|---|
| Nondiabetic subjects (n = 681) | ||
| Model 1 | 0.14 | <0.001 |
| Model 2 | 0.04 | NS |
| Model 3 | −0.01 | NS |
| Type 2 diabetic subjects (n = 57) | ||
| Model 1 | 0.31 | 0.02 |
| Model 2 | 0.37 | 0.0056 |
| Model 3 | 0.40 | 0.0049 |
Model 1 unadjusted; model 2 adjusted for age and sex; model 3 adjusted for age, sex, diastolic and systolic blood pressure, BMI, current smoking, plasma glucose, and total, LDL, and HDL cholesterol. NS, not significant.
References
Address correspondence to G.F.H. Diercks, MD, Department of Clinical Pharmacology, University of Groningen, A. Deusinglaan 1, 9713 AV Groningen, the Netherlands. E-mail: [email protected].
