Urinary albumin excretion in lean, overweight and obese glucose tolerant individuals: its relationship with dyslipidaemia, hyperinsulinaemia and blood pressure

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Abstract
The presence of microalbuminuria has become an important tool for therapeutic intervention. In this study we investigated whether the dysmetabolic syndrome of obesity was associated with or could occur in the absence of microalbuminuria. The study was conducted in 71 clinically healthy, glucose tolerant Hispanics (age: 43 ± 1.4 years, body mass index (BMI): 28.7 ± 0.6 kg/m2, systolic blood pressure (SBP): 117 ± 2 mm Hg, diastolic blood pressure (DBP): 77 ± 1.3 mm Hg, urinary albumin excretion: 10.2 ± 0.6 mg/24 h). Subjects were classified as lean (BMI 25 30 kg/m2). Greater BMI was associated with higher body weight, waist-to-hip ratio (WHR), BP, fasting insulin, triglyceride, post glucose load insulin and glucose, and lower high-density lipoprotein (HDL) cholesterol levels. However, no significant differences in the urinary albumin excretion (mg/24 h) were found between lean (9.0 ± 0.9; median: 9.1), overweight (11.3 ± 1.2; median: 10.5) and obese (11.1 ± 1.2; median: 9.7) subjects. In addition, microalbuminuria (urinary albumin excretion >30 mg/24 h) was not found in any of the study subjects. For all subjects combined, as well as for each of the groups separately, the urinary albumin excretion was unrelated to the BMI, WHR, body weight, triglyceride, cholesterol (total, LDL or HDL), fasting or post-load glucose and insulin plasma concentrations. Neither in females nor in males, abdominal fat accumulation was associated with an increase in the urinary albumin excretion. However, in the obese groups, urinary albumin excretion was strongly related to the level of SBP (r2: 0.67; P < 0.0001) and DBP (r2: 0.55; P < 0.0001). In summary, obesity, hyperinsulinaemia and dyslipidaemia per se are not determinants of increased albumin excretion. However, in the obese subjects, the BP, particularly the SBP, was a strong determinant of the level of albumin in the urine. Microalbuminuria may occur later in the course of the dysmetabolic syndrome, due to worsening of hypertension and development of hyperglycaemia.