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Increased Proximal Tubular Sodium Reabsorption in Hypertensive Patients with Type 2 Diabetes
Author(s) -
Mbanya J.C.,
Thomas T. H.,
Taylor R.,
Alberti K. G. M. M.,
Wilkinson R.
Publication year - 1989
Publication title -
diabetic medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.474
H-Index - 145
eISSN - 1464-5491
pISSN - 0742-3071
DOI - 10.1111/j.1464-5491.1989.tb01238.x
Subject(s) - medicine , endocrinology , renal sodium reabsorption , plasma renin activity , diabetes mellitus , sodium , reabsorption , creatinine , renal function , renin–angiotensin system , kidney , blood pressure , chemistry , organic chemistry
Hyperinsulinaemia and sodium retention have been studied in 22 Type 2 diabetic patients (10 normotensive, 12 hypertensive) and 10 normal control subjects matched for age, sex, and body mass index. Exchangeable sodium was similar in the three groups. Plasma renin activity and plasma angiotensin II were lower in both groups of diabetic patients than in the normal control subjects ( p <0.01). Plasma atrial natriuretic peptide was increased in the hypertensive patients (7.3 ± 1.1 vs normotensive 4.7 ± 1.1 pmol I −1 and control 4.0 ± 0.2 pmol I −1 , p <0.01). Fractional lithium clearance, a measure of sodium clearance from the proximal tubule, was decreased (18.5 ± 1.4, p <0.01) and fractional excretion of sodium in the distal tubule was increased (6.66 ± 0.66, p <0.01) in untreated hypertensive diabetic patients compared with both normotensive diabetic patients (25.3 ± 1.6 and 3.96 ± 0.52 respectively) and normal control subjects (25.2 ± 2.9 and 3.31 ± 0.38, respectively). Fasting serum insulin was higher in hypertensive than in normotensive diabetic patients (18.5 ± 3.0 vs 10.7 ± 1.1 mU I −1 , p <0.01) and higher in both groups than in normal control subjects (5.6 ± 0.1 mU I −1 , both p <0.01). Creatinine clearance was higher in both groups of diabetic patients than in normal control subjects ( p <0.05). Thus there appears to be increased proximal renal tubular sodium reabsorption in these hypertensive Type 2 diabetic patients, matched by a reduction in distal sodium reabsorption so that net sodium excretion was maintained. This was associated with fasting hyperinsulinaemia.