To evaluate whether erythrocyte levels of polyamines spermidine and spermine (expressed in nmol/ml packed erythrocytes [PRBCs]) are modified in insulin-dependent diabetes mellitus (IDDM) and are associated with the presence of retinopathy or nephropathy.
We studied erythrocyte spermidine and spermine levels in 38 IDDM patients with or without persistent microalbuminuria (urinary albumin excretion rate [AER] between 20 and 200 μg/min), macroalbuminuria (AER >200 μg/min), or retinopathy compared with 60 sex- and age-matched control subjects.
Mean ± SD erythrocyte spermine content was similar in both diabetic (9.7 ± 5.5 nmol/ml PRBCs) and control (8.8 ± 3.5 nmol/ml PRBCs) subjects, whereas spermidine was higher in diabetic (19.1 ± 7.2 nmol/ml PRBCs) than in control (14.5 ± 4 nmol/ml PRBCs, P = 0.0007) subjects. Moreover, spermidine was significantly higher in the groups with microalbuminuria (n = 11, 22.5 ± 9.2 nmol/ml PRBCs) and macroalbuminuria (n = 4, 22.2 ± 5.7 nmol/ml PRBCs) than in both normoalbuminuric (n = 23, 16.9 ± 5.6 nmol/ml PRBCs) and control (F = 9.78, P = 0.0001) subjects, and correlated with log AER (r = 0.41, P = 0.009). Similarly, proliferative retinopathy was associated with a significant increase in spermidine (n = 5, 20 ± 7 nmol/ml PRBCs compared with control subjects [P = 0.0009]).
Our data suggest that erythrocyte spermidine content is increased in IDDM patients associated with both diabetic nephropathy and advanced retinopathy.