Microalbuminuria, brain vasomotor reactivity, carotid and kidney arterial flow in Type 2 diabetes mellitus.

Diabetic microangiopathy produces widespread small vessel impairment which particularly affects renal glomeruli functions. Microalbuminuria is the earliest marker of microangiopathic kidney disease and has also recently been recognised as a marker of macroangiopathic cardiovascular involvement. To determine correlations between daily microalbuminuria, local microangiopathic kidney damage, systemic macroangiopathic involvement and functional brain microcirculation, 70 Type 2 diabetic subjects who were diagnosed more than 5 years ago underwent carotid (to determine index of macro- and microangiopathy) and interlobar kidney artery color Doppler (to determine microangiopathic involvement), transcranial Doppler (to determine alterations in brain vasomotor reserve), and evaluation of daily albumin excretion rate. All the indices of microcirculatory involvement in the kidney, brain and small vessels downstream-from the carotid arteries were closely related (for all p<0.001) but never correlated with the macroangiopathy index. Daily microalbuminuria correlated with all the micro- (p<0.0001) and macroangiopathic (p<0.005) Doppler indices. These findings confirm that microangiopathy is the main cause of the diabetic increase in the albumin excretion rate and support the view that microalbuminuria can be considered a powerful biomarker of widespread macroangiopathy. Our results suggest microalbuminuria may also identify cerebrovascular diabetic involvement, as it predicts both macroangiopathic carotid alteration and microvascular brain impairment.