Keywords Insulin-dependent diabetes mellitus
glomerular filtration rate
renal sodium reabsorption.
Springer Online Journal Archives 1860-2000
Summary To evaluate the role of insulin and hypertriglyceridaemia in the regulation of renal haemodynamics and sodium handling in insulin-dependent diabetes mellitus (IDDM), 11 IDDM patients without microalbuminuria and 13 weight-, age-, protein intake- and sex-matched healthy control subjects were studied. Clearances of inulin (Cin), para-amino-hippuric acid (CPAH), sodium (CNa), and lithium (CLi) were measured in four 60-min clearance periods (periods I, II, III and IV) during isoinsulinaemia with lipid emulsion infusion (study 1), a hyperinsulinaemic isoglycaemic clamp with Intralipid infusion (study 2), and during time-controlled isoinsulinaemia (study 3). We found that Cin, CPAH and filtration fraction were comparable in IDDM and control subjects, whereas CNa was decreased in diabetic subjects (2.01 ± 1.11 vs 3.03 ± 1.32 ml/min; p 〈 0.05) due to elevations of proximal tubular fractional and absolute reabsorptions of sodium (p 〈 0.05). Insulin infusion did not affect Cin, increased CPAH (p 〈 0.05) and, consequently, lowered the filtration fraction (p 〈 0.01) in both groups. While acute hyperinsulinaemia resulted in increases in distal tubular fractional and absolute reabsorptions of sodium (p 〈 0.01) contributing to a fall in CNa (p 〈 0.01) in control subjects, in diabetic subjects the sodium-retaining effect of insulin was not significant. The lipid emulsion did not alter any of the estimated parameters. We conclude that IDDM without microalbuminuria is associated with a tendency to sodium retention which is not aggravated by insulin when compared to control subjects. Acutely induced hypertriglyceridaemia does not alter renal haemodynamics or renal sodium handling. [Diabetologia (1996) 39: 1074–1082]
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