The relationship of heart rate and heart rate variability to non-diabetic fasting glucose levels and the metabolic syndrome: The Cardiovascular Health Study

• Published in: Diabetic medicine 2007-08, Vol.24 (8), p.855-863
• Main Authors: Stein, P. K., Barzilay, J. I., Domitrovich, P. P., Chaves, P. M., Gottdiener, J. S., Heckbert, S. R., Kronmal, R. A.
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; Arrhythmias, Cardiac - etiology; Biological and medical sciences; Blood Glucose - metabolism; Diabetes. Impaired glucose tolerance; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Fasting - blood; fasting glucose; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Glucose Intolerance - metabolism; Heart Rate; heart rate variability; Humans; Male; Medical sciences; metabolic syndrome; Metabolic Syndrome - blood; Metabolic Syndrome - complications; Risk Factors; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology
• ISSN: 0742-3071; 1464-5491
• DOI: 10.1111/j.1464-5491.2007.02163.x

Background  Increased heart rate (HR) and diminished heart rate variability (HRV) are signs of early cardiovascular autonomic neuropathy. We tested the hypotheses that increased HR and diminished HRV are present in people: (i) with increased fasting glucose (FG) levels not in the range of diabetes mellitus (DM), and (ii) in people with the metabolic syndrome (MetS) independent of elevated FG levels. Methods  HR and HRV were determined in 1267 adults (mean age 72 years) who had Holter monitoring and FG measures: 536 had normal FG levels (NORM, FG 4.5–5.5 mmol/l), 363 had mildly impaired FG (IFG‐1, FG 5.6–6.0 mmol/l), 182 had significantly impaired FG (IFG‐2, FG 6.1–6.9 mmol/l) and 178 had DM (FG > 6.9 mmol/l or use of glucose‐lowering agents/insulin). HR and HRV in NORM/IFG‐1 was further compared by the number of components of the MetS and compared by the presence or absence of MetS in IFG‐2/DM. Results  HRV indices were more impaired in IFG‐2 and DM than in NORM or IFG‐1. There were few differences in HRV indices between NORM and IFG‐1 or between IFG‐2 and DM. In NORM/IFG‐1 participants, having ≥ 2 components of the MetS was associated with a greater decrease in HRV compared with having no or one components. In IFG‐2/DM participants, MetS was associated with decreased HRV compared with no MetS. Conclusions  Increased HR and diminished HRV occur in the non‐diabetic FG range. Diminished HRV is associated with the MetS, independent of FG levels. Both these results suggest that factors associated with increasing non‐diabetic FG levels and the MetS play a role in the onset of cardiac autonomic impairment.