Urinary insulin levels in health and disease—a concise review

Abstract

SummaryThe kidneys are the most important extrahepatic site of insulin breakdown and play a significant role in regulating the systemic insulin level in normal subjects. In man, a renal arteriovenous insulin concentration difference of about 30 % has been measured, and since 'insulin clearance' values are less than the glomerular filtration rates, insulin is probably removed from blood by a combination of filtration and tubular secretion. In normal subjects a constant fraction of circulating insulin is removed by the kidney. This fraction is independent of the arterial concentration but varies with creatinine clearance. Of the amount filtered, most is completely resorbed and degraded by the cells of the proximal convoluted tubules. These cells have a high insulinase content and recent evidence would point to the possible existence of a renal tubular transport mechanism for insulin. The amount of insulin excreted in the urine is small and does not exceed 2 % of the filtered load. In diabetics the insulin requirements often decrease with progressive renal failure.

Disorders of glucose metabolism: post mortem analyses in forensic cases–part II

“…Not recommended to measure the insulin level are tissue samples of liver, brain or kidney [66]. Coe reported Table 1 Reference levels of relevant peptides in blood (I/C-ratio=molar ratio of insulin to C-peptide; insulin: μU/ml×6=pmol/l, C-peptide: μg/ l×0.28=nmol/l, proinsulin: ng/l×0.11=pmol/l) Reference range in urine for non-diabetics 2.76-6.9 μU/ml [101,102,147,148] 40-150 μg/l, 32-165 μg/l, 10-120 μg/l [101,102,147,148] that insulin and C-peptide rarely penetrate the blood-vitreous barrier [67]. In one case of an insulin intoxication, Winston et al [68] measured vitreous insulin in a concentration of 31 μU/ml but there are no reference data or validated methods for VF and cerebrospinal fluid.…”

Insulin Metabolism and Degradation*

“…The pattern of uptake is consistent with the handling of other proteins and peptides with endocytosis, endocytotic vesicles, and lysosomal metabolism. Very little intact insulin is found in the urine (189).…”

The effects of insulin and glucose on growth and expression of mar regulon in E. coli

“…Furthermore, insulin is known to highly conserved protein among various taxonomic kingdoms and its blood level is approximate 10µIU/mL in a healthy individual. The reabsorption only occurs for the 98% of the total insulin while the 2% of it excreted in urine [20][21][22]. Two insulin concentrations used in the present study have been determined as 2 and 20 times more than the normal blood levels.…”