Introduction: This study was designed to assess possible alterations in heart rate (HR), heart rate variability (HRV) and circulating serum levels of proinflammatory cytokines in patients with impaired glucose tolerance (IGT).
Methods: Forty-five patients, aged 34-68 years, with IGT were compared with 28 age-matched healthy controls. Using a 24-hour ambulatory electrocardiogram, we calculated mean HR during daytime (HR-D), night-time (HR-N) and the entire 24-hour period (HR-24h), as well as time domain HRV parameters. From blood samples interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-a) and its soluble receptor (sTNFRII) were also calculated by immunoassay.
Results: Patients showed higher mean HR compared to controls and significantly elevated circulating levels of TNF-a, sTNFRII, and IL-6. Pearson correlation analysis showed that TNF-a was positively correlated with mean HR-D (r: 0.304, p=0.042). IL-6 was also positively correlated with mean HR-24h (r: 0.299, p=0.046) and with mean HR-D (r: 0.410, p=0.005).
Conclusion: IGT patients have an increased HR and elevated cytokine levels. These changes could serve as an index of the primary atherosclerotic process.