Aims/hypothesis: To investigate the influence of angiotensin converting enzyme inhibitors and beta blockers on the progression of early diabetic glomerulopathy.
Methods: Thirteen patients with Type I (insulin-dependent) diabetes mellitus (mean age 18.8 years) with microalbuminuria 31 (19-160) microg/min were randomised to treatment with enalapril (group 1, n = 7) or metoprolol (group 2, n = 6). Renal biopsies were taken before and after 38 (36-48) months of treatment. Albumin excretion rate, blood pressure and HbA1c were measured every third month. A reference group without antihypertensive treatment (group 3, n = 9), with similar age, diabetes duration and degree of microalbuminuria as group 1 and 2, had baseline and follow-up renal biopsies taken previously with an interval of 26-34 months, analysed at the same laboratory. Glomerular structures were measured by stereological methods.
Results: Measurements of basement membrane thickness, mesangial and matrix volume fractions were similar among groups at baseline. Structural variables were only increased in group 3 at follow-up. Delta values in basement membrane thickness and diabetic glomerulopathy index per 24 months were lower in group 1 and 2 than in group 3 (p < 0.05). Microalbuminuria returned to normal in group 1 and 2 only. Decreased albumin excretion rate tended to inversely correlate with increased basement membrane thickness (p = 0.08) and diabetic glomerulopathy index (p = 0.05). Mean HbA1c was similar between groups. Mean diastolic blood pressure was lower in group 1 and 2 than in group 3 (p < 0.01). Mean HbA1c and mean diastolic blood pressure correlated to changes in basement membrane thickness, mesangial volume fraction and diabetic glomerulopathy index (p < 0.05).
Conclusion/interpretation: Contrary to findings in the group without antihypertensive treatment, no progression of glomerulopathy was seen in those treated with enalapril or metoprolol.