Plasma levels of tissue inhibitor of metalloproteinase-1 in patients with type 1 diabetes mellitus associate with early diabetic neuropathy and nephropathy

Background: Tissue inhibitor of metalloproteinase-1 (TIMP-1) has been suggested as a marker for abnormal regulation of tissue remodelling in type 1 diabetes. Metalloproteinase-9 (MMP-9) has been associated with matrix turnover, and Neutrophil gelatinase associated lipocalin (NGAL) is a marker of tubular injury in diabetic nephropathy. The aim was to analyse these biomarkers to unmask early diabetic complications. Methods: Thirty-three type 1 diabetes patients, aged 20-35 years, and disease duration 20 +/- 5.3 years were included. Along with clinical examination, neurophysiological measurements, routine biochemistry, plasma concentrations of TIMP-1, MMP-9 and NGAL were determined with immunoenzymatic techniques. Results: TIMP-1 correlated with abnormal unilateral and bilateral vibratory sense foot perception (r = -0.49 and r = -0.51, respectively), foot neuropathy impairment assessment score (NIA; r = -0.55), neuropathy symptom assessment score (r = 0.42), microalbuminuria (r = 0.50) and eGFR (r = -0.45). MMP-9 correlated with impaired foot NIA (r = 0.51). Multiple regression analysis showed an association for TIMP-1 (p = 0.004) with impaired neurophysiological examinations and renal dysfunction along with NGAL (p = 0.016 and p = 0.015 respectively). Conclusions: This study suggests that plasma levels of TIMP-1, MMP-9 and NGAL may serve as useful biomarkers in unravelling subclinical neuropathy and nephropathy in type 1 diabetes.