Variations of urinary protein excretion and α1-antitrypsin molecular size by glycemic control in type 2 diabetic patients

We tried to determine the variations of levels and molecular heterogeneities of various proteins which occur in type 2 diabetes patients during short-term hospitalization for glycemic control. Type 2 diabetes patients were classified into 2 groups: only oral diabetes medicine therapy (group I) and only insulin and/or insulin plus oral diabetes medicine therapy (group II). All urinary proteins in group I tended to decrease on discharge day. Tamm-Horsfall protein (THP) levels of group II significantly increased on discharge day. There were significant correlations between each protein except with THP on day of admission and discharge of group I. In addition, there were no correlations between THP and other proteins except with α1-antitrypsin (α1-AT) in group II. Comparison of blood glucose level and HbA1c on admission day and first clinic day after discharge revealed that HbA1c level on discharge day was significantly lower in group II. We examined the molecular size of various proteins by SDS-PAGE and western blotting. In both groups, 9 α1-AT bands of different molecular sizes were detected besides a main band, but in group II, a 43 kDa α1-AT fragment, in urine collected closer to discharge day was found to be more densely stained than that in urine collected on admission day. These results revealed that glycemic control by insulin increased THP levels, remarkably reduced other protein levels, and caused urinary α1-AT to be of low molecular size.