Estimation of transforming growth factor-beta 1 as a marker of renal injury in type II diabetes mellitus

OBJECTIVE: To evaluate the serum transforming growth factor-beta 1 level in type II diabetic patients with diabetic nephropathy (DN) and to assess its use as a marker of renal injury in type II diabetes.

METHODS: Sixty patients with type II diabetes mellitus (DM), who attended the outpatient internal medicine clinic in Cairo University Hospital, Egypt from January 2003 to March 2003, were the subjects of the present study and compared to 10 healthy age- and gender- matched control subjects They were divided into 6 major groups according to degree of metabolic control, as determined by glycosylated hemoglobin (HbA1c), the rate of urinary albumin excretion (UAE) and serum creatinine level. Serum transforming growth factor-beta 1 level was assessed by enzyme linked immunosorbent assay (ELISA).

RESULTS: Serum transforming growth factor-beta 1 level was significantly increased in micro albuminuric (UAE 20-200 ug/minute), macro albuminuric (UAE >200 ug/minute) and overtly nephropathic diabetic patients with renal impairment compared to healthy controls (p<0.05). In addition, serum transforming growth factor-beta 1 level was significantly increased in type II diabetic patients with poor glycemic control (HbA1c >7.6%) compared to patients with good glycemic control (HbA1c 5.5-7.6%). Serum transforming growth factor-beta 1 level was significantly increased in hypertensive DM patients compared to normotensive DM patients (p<0.05). There was a strong correlation between serum transforming growth factor-beta 1 level and HbA1c, blood urea, serum creatinine and 24-hour urinary protein excretion (p<0.01).

CONCLUSION: Our data strongly support the hypothesis that hyperglycemia may trigger the activation of transforming growth factor-beta 1 which in turn mediates progressive renal damage in type II DM. Increased serum transforming growth factor-beta 1 may be useful as a marker of diabetic renal disease as it shows a close association with the parameters of renal injury in type II diabetes.