Regulation of whole-body leucine metabolism with insulin during mixed-meal absorption in normal and diabetic humans

• Published in: Diabetes (New York, N.Y.) Vol. 37; no. 5; pp. 512 - 519
• Main Authors: Tessari, P., Pehling, G., Nissen, S. L., Gerich, J. E., Service, F. J., Rizza, R. A., Haymond, M. W.
• Format: Journal Article
• Language: English
• Published: American Diabetes Association 01.05.1988
• ISSN: 0012-1797; 1939-327X; 0012-1797
• DOI: 10.2337/diabetes.37.5.512

Regulation of whole-body leucine metabolism with insulin during mixed-meal absorption in normal and diabetic humans. P Tessari , G Pehling , S L Nissen , J E Gerich , F J Service , R A Rizza and M W Haymond Department of Pediatrics, Mayo Clinic and Foundation, Rochester, Minnesota 55905. Abstract To determine the effects of insulin on dietary and endogenous leucine metabolism, five normal subjects, seven insulin-insufficient insulin-dependent (IDDM) diabetic patients, and five diabetic patients controlled with continuous subcutaneous insulin infusion (CSII) were studied before and for 8 h after ingestion of a chemically defined elemental test meal (10 cal/kg) containing crystalline amino acids. L-[1-14C]leucine was included in the meal to trace the entry and oxidation of the dietary leucine. Total (meal + endogenous) entry of leucine into the circulation was estimated with a constant infusion of [2H3]leucine. Postabsorptive and meal-related increases in the plasma leucine concentration were greater (P less than .05) in the insulin-insufficient IDDM than in the normal subjects but returned to near-normal values with CSII. Baseline leucine flux was approximately 40% greater in the insulin-insufficient IDDM than in normal subjects (2.17 +/- 0.17 vs. 1.55 +/- 0.15 mumol.kg-1.min-1, respectively; .05 less than P less than .01) but were near normal during CSII treatment (1.85 +/- 0.25 mumol.kg-1.min-1). Furthermore, total leucine entry during meal absorption was greater in the insulin-insufficient IDDM (1.41 +/- 0.10 mmol.kg-1.8 h-1) than in either normal (0.96 +/- 0.08 mmol.kg-1.8 h-1, P less than .01) or IDDM subjects during CSII treatment (1.09 +/- 0.11 mmol.kg-1.8 h-1, P less than .05). Fractional oxidation (approximately 40-50%) and entry of dietary leucine were similar in all three groups.