A total of 359 Wanigelas from Papua New Guinea and 1041 Nauruans had urinary albumin concentrations (UAC), serum insulin, and a number of cardiovascular disease (CVD) risk factors measured during population-based surveys of non-insulin-dependent diabetes mellitus. These data were used to explore the hypothesis that microalbuminuria is closely associated with insulin resistance and the metabolic syndrome. In both Nauruans and Wanigelas, worsening glucose tolerance was associated with increasing prevalence of micro- and macroalbuminuria. Within each category of glucose tolerance, microalbuminuria was associated with general worsening of cardiovascular risk factors including lipid concentrations, blood pressure and obesity, although few of the associations were statistically significant. Correlations between UAC and markers of insulin resistance (fasting insulin, fasting insulin/glucose ratio and HOMAS%, a computer-modelled estimate of insulin sensitivity) were weak and inconsistent irrespective of glucose tolerance status. Relationships between insulin sensitivity and urinary albumin in normoglycaemic Wanigelas and Nauruans, and in diabetic Nauruans, were no longer significant after adjusting for fasting glucose and body mass index. While microalbuminuria in Nauruans and Wanigelas was associated with cardiovascular risk factors irrespective of glucose tolerance, it seems unlikely on the basis of these results that the relationship is mediated through a common association with insulin resistance.