Betaine and Trimethylamine-N-Oxide as Predictors of Cardiovascular Outcomes Show Different Patterns in Diabetes Mellitus: An Observational Study

• Published in: PloS one Vol. 9; no. 12; p. e114969
• Main Authors: Lever, Michael, George, Peter M., Slow, Sandy, Bellamy, David, Young, Joanna M., Ho, Markus, McEntyre, Christopher J., Elmslie, Jane L., Atkinson, Wendy, Molyneux, Sarah L., Troughton, Richard W., Frampton, Christopher M., Richards, A. Mark, Chambers, Stephen T.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 10.12.2014; Public Library of Science (PLoS)
• Subjects: Acute Coronary Syndrome - blood; Acute Coronary Syndrome - complications; Aged; Aged, 80 and over; Angina; Betaine; Betaine - blood; Biochemistry; Biology and Life Sciences; Biomarkers - blood; Cardiovascular diseases; Cardiovascular Diseases - blood; Case-Control Studies; Death; Diabetes; Diabetes mellitus; Diabetes Mellitus, Type 2 - blood; Diabetes Mellitus, Type 2 - complications; Dimethylglycine; Ethics; Female; Glomerular filtration rate; Health risk assessment; Health risks; Heart; Heart diseases; Homocysteine; Humans; Kaplan-Meier Estimate; Kidney diseases; Laboratories; Liver; Male; Medicine; Medicine and Health Sciences; Metabolism; Metabolites; Methylamines - blood; Middle Aged; Mortality; Myocardial infarction; Observational studies; Pathology; Population; Proportional Hazards Models; Regression analysis; Regression models; Risk Factors; Rodents; Trimethylamine; Trimethylamine-N-oxide; New Zealand
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0114969

Betaine is a major osmolyte, also important in methyl group metabolism. Concentrations of betaine, its metabolite dimethylglycine and analog trimethylamine-N-oxide (TMAO) in blood are cardiovascular risk markers. Diabetes disturbs betaine: does diabetes alter associations between betaine-related measures and cardiovascular risk? Plasma samples were collected from 475 subjects four months after discharge following an acute coronary admission. Death (n = 81), secondary acute MI (n = 87), admission for heart failure (n = 85), unstable angina (n = 72) and all cardiovascular events (n = 283) were recorded (median follow-up: 1804 days). High and low metabolite concentrations were defined as top or bottom quintile of the total cohort. In subjects with diabetes (n = 79), high plasma betaine was associated with increased frequencies of events; significantly for heart failure, hazard ratio 3.1 (1.2-8.2) and all cardiovascular events, HR 2.8 (1.4-5.5). In subjects without diabetes (n = 396), low plasma betaine was associated with events; significantly for secondary myocardial infarction, HR 2.1 (1.2-3.6), unstable angina, HR 2.3 (1.3-4.0), and all cardiovascular events, HR 1.4 (1.0-1.9). In diabetes, high TMAO was a marker of all outcomes, HR 2.7 (1.1-7.1) for death, 4.0 (1.6-9.8) for myocardial infarction, 4.6 (2.0-10.7) for heart failure, 9.1 (2.8-29.7) for unstable angina and 2.0 (1.1-3.6) for all cardiovascular events. In subjects without diabetes TMAO was only significant for death, HR 2.7 (1.6-4.8) and heart failure, HR 1.9 (1.1-3.4). Adding the estimated glomerular filtration rate to Cox regression models tended to increase the apparent risks associated with low betaine. Elevated plasma betaine concentration is a marker of cardiovascular risk in diabetes; conversely low plasma betaine concentrations indicate increased risk in the absence of diabetes. We speculate that the difference reflects control of osmolyte retention in tissues. Elevated plasma TMAO is a strong risk marker in diabetes.