Improved metabolic control does not alter the charge-dependent glomerular filtration of albumin in uncomplicated type 1 (insulin-dependent) diabetes

The selectivity index, i.e. clearance of non glycated albumin/clearance of glycated albumin was studied in fourteen patients with Type 1 (insulin-dependent) diabetes and normal urinary albumin excretion. The index was increased above one in all patients, and correlated significantly to HbA1c. It was, however, unaffected by 12 weeks of improved metabolic control with a mean decline in HbA1c of 1.9% in seven patients. We conclude that the increased electronegative charge of the glomerular filtration barrier observed in uncomplicated diabetes is related to long term metabolic control but not reversible during twelve weeks of strict metabolic control. This indicates a slow turnover of the components responsible for the increased charge selectivity in uncomplicated diabetes.