Combining glomerular basement membrane and tubular basement membrane assessment improves the prediction of diabetic end-stage renal disease

Background: To address the prognostic value of combining tubular basement membrane (TBM) and glomerular basement membrane (GBM) thickness in diabetic nephropathy (DN). Methods: This retrospective study enrolled 110 patients with type 2 diabetes and biopsy-proven DN from 2011 to 2018. The pathological findings were confirmed according to the Renal Pathology Society classifications. GBM and TBM thicknesses were determined using the Haas' direct measurement/arithmetic mean method and orthogonal intercept method, respectively. Cox proportional hazard models were used to investigate the hazard ratios (HRs) for the influence of combined GBM and TBM thickness for predicting end-stage renal disease (ESRD). Results: Patients were assigned to three groups according to the median GBM and TBM thickness: GBM^loTBM^lo (GBM < 681 nm and TBM < 1200 nm), GBM^hiTBM^lo/GBM^loTBM^hi (GBM ≥ 681 nm and TBM < 1200 nm, or GBM < 681 nm and TBM ≥ 1200 nm), and GBM^hiTBM^hi (GBM ≥ 681 nm and TBM ≥ 1200 nm). The GBM^hiTBM^lo/GBM^loTBM^hi and GBM^hiTBM^hi groups displayed poorer renal function, a more severe glomerular classification and interstitial inflammation, and poorer renal survival rates than the GBM^loTBM^lo group The GBM^hiTBM^lo/GBM^loTBM^hi and GBM^hiTBM^hi groups had adjusted HRs of 1.49 (95% confidence interval [CI], 1.21-9.75) and 3.07 (95% CI, 2.87-12.78), respectively, compared with the GBM^loTBM^lo group. Conclusions: TBM thickness enhanced GBM thickness for renal prognosis in patients with type 2 diabetes.