Albuminuria and glomerular filtration rate in type 2 diabetes mellitus

The aim of this paper was to analyze the relation between glomerular filtration rate (GFR) and albumin excretion rate (AER) in subjects with type 2 diabetes.

Three hundred thirteen type 2 diabetic patients attending Diabetes Centre, Malta, were studied between 2008 and 2009. GFR was estimated using the Modified Diet Renal Disease (MDRD) formula while two spot measurements of urinary AER were used to determine albuminuria.

Forty-nine patients were hyperfiltrating, of whom 69% were normoalbuminuric, 24% microalbuminuric, and 6% macroalbuminuric; 229 subjects had normal eGFR; of these 67% were normoalbuminuric, 27% microalbuminuric and 6% macroalbuminuric; 35 subjects had eGFR<60mL/min/1.73 m2, of whom 43% were normoalbuminuric, 37% microalbuminuric and 20% macroalbuminuric. No association was found between eGFR and AER in subjects with hyperfiltration (P=0.39); however eGFR was strongly correlated with AER in subjects with eGFR <60ml/min/1.73 m2 (r= -0.376; P=0.026). In multinomial logistic regression analysis, eGFR was significantly associated with albuminuria in non-hyperfiltrating, but not in hyperfiltrating, subjects.

Our data suggests that hyperfiltration and albuminuria occur independently of each other in the early stages of DN, but the decline in eGFR and albuminuria follow a parallel course in later stages of DN suggesting that they may share common pathophysiological mechanisms or they may be causally linked.