Acute and long-term effect of antihypertensive treatment on exercise-induced albuminuria in incipient diabetic nephropathy

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Abstract
The aim of the study was to clarify whether antihypertensive treatment could affect the systolic blood pressure (SBP) and urinary albumin excretion (UAE) in diabetics during exercise (450 kpm/min, followed by 600 kpm/min, 20 min each). Young male insulin-dependent diabetics with normal UAE (n=9) and diabetics with incipient nephropathy (n=7) were examined in an acute study. Five patients with incipient diabetic nephropathy participated in a long-term study. Incipient diabetic nephropathy is defined as persistently elevated UAE (> 15 μg/min), but no clinical proteinuria. In the acute study, using placebo/metoprolol 10 mg i.v. in patients with normal UAE, the maximal SBP at 600 kpm/min was reduced by 17 mmHg±10 (SD) (2p<1.0%) and the maximal SBP at 600 kpm/min in the patients with incipient nephropathy was reduced by 15 mmHg±11 (SD) (2p<1.0%). However, no difference was observed in UAE, in patients with normal UAE or those with incipient nephropathy. Five of the patients with incipient nephropathy were followed with repeated exercise tests before and during 2.6 years of antihypertensive treatment, using metoprolol 200 mg/24 h and subsequently also hydroflumethiazid 25 mg/24 h. The maximal SBP at 600 kpm/min at the end of the study compared to the pretreatment level was reduced by 38 mmHg±12 (SD) (2p<1.0%), and furthermore the exercise-induced elevated UAE was reduced by 61%±29 (SD) (2p = 2.0%). It is concluded that acute reduction in the exercise-induced elevated SBP is not associated with a reduction in UAE, but long-term antihypertensive treatment reduces both the exercise-induced elevated SBP and the exercise-induced increased level in UAE in diabetics with early nephropathy.