Effects of insulin deprivation and treatment on homocysteine metabolism in people with type 1 diabetes

Haitham S. Abu-Lebdeh, Rocco Barazzoni, Shon E. Meek, Maureen L. Bigelow, Xuan Mai T. Persson, K. Sreekumaran Nair

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

Context: Abnormal homocysteine metabolism may contribute to increased cardiovascular death in type 1 diabetes (T1DM). Amino acid metabolism is altered in T1DM. In vitro, insulin reduces hepatic catabolism of homocysteine by inhibiting liver transsulfuration. It remains to be determined whether methionine-homocysteine metabolism is altered in T1DM. Objective: We sought to determine whether insulin deficiency during insulin deprivation or high plasma insulin concentration after insulin treatment alters homocysteine metabolism in T1DM. Design: This was an acute interventional study with paired and comparative controls. Setting: The study was conducted at a general clinical research center. Patients and Intervention: We used stable isotope tracers to measure methionine-homocysteine kinetics in six patients with T1DM during insulin deprivation (I-) and also during insulin treatment (I+) and compared them with nondiabetic controls (n = 6). Main Outcome Measures: Homocysteine kinetics (transmethylation, transsulfuration, and remethylation) were from plasma isotopic enrichment of methionine and homocysteine and 13CO 2. Results: T1DM (I-) had lower rates of homocysteine-methionine remethylation (P < 0.05 vs. control and I+). In contrast, transsulfuration rates were higher in I- than controls and I+ (P < 0.05). Insulin treatment normalized transsulfuration and remethylation (P < 0.05 vs. I- and P > 0.8 vs. control). Plasma homocysteine concentrations were lower in T1DM (P < 0.05 vs. control during both I- and I+), which may be explained by increased homocysteine transsulfuration. Thus, significant alterations of methionine-homocysteine metabolism occur during insulin deprivation in humans with T1DM. Conclusions: Insulin plays a key role in the regulation of methionine-homocysteine metabolism in humans, and altered homocysteine may occur during insulin deficiency in type 1 diabetic patients.

Original languageEnglish (US)
Pages (from-to)3344-3348
Number of pages5
JournalJournal of Clinical Endocrinology and Metabolism
Volume91
Issue number9
DOIs
StatePublished - Jan 1 2006

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Endocrinology
  • Clinical Biochemistry
  • Biochemistry, medical

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