Increased prevalence of cardiac autonomic dysfunction at different degrees of glucose intolerance in the general population: the KORA S4 survey

Abstract

Aims/hypothesis Cardiac autonomic nervous dysfunction (CAND) raises the risk of mortality, but the glycaemic threshold at which it develops is unclear. We aimed to determine the prevalence of, risk factors for and impact of CAND in glucose intolerance and diabetes. Methods Among 1,332 eligible participants aged 55-74 years in the population-based cross-sectional KORA S4 study, 130 had known diabetes mellitus (k-DM), and the remaining 1,202 underwent an OGTT. Heart rate variability (HRV) and QT variability were computed from supine 5 min ECGs. Results In all, 565 individuals had normal glucose tolerance (NGT), 336 had isolated impaired fasting glucose (i-IFG), 72 had isolated impaired glucose tolerance (i-IGT), 151 had combined IFG-IGT (IFG-IGT) and 78 had newly detected diabetes mellitus (n-DM). Adjusted normal HRV limits were defined in the NGT population (5th and 95th percentiles). Three HRV measures were more frequently abnormal in those with k-DM, n-DM, IFG-IGT and i-IFG than in those with NGT (p<0.05). The rates of CAND (≥2 of 4 HRV indices abnormal) were: NGT, 4.5%; i-IFG, 8.1%; i-IGT, 5.9%; IFG-IGT, 11.4%; n-DM, 11.7%; and k-DM, 17.5% (p<0.05 vs NGT, except for i-IGT). Reduced HRV was associated with cardiovascular risk factors used to construct a simple screening score for CAND. Mortality was higher in participants with reduced HRV (p<0.05 vs normal HRV). Conclusions/interpretation In the general population aged 55-74 years, the prevalence of CAND is increased not only in individuals with diabetes, but also in those with IFG-IGT and, to a lesser degree, in those with i-IFG. It is associated with mortality and modifiable cardiovascular risk factors which may be used to screen for diminished HRV in clinical practice.

Inflammatory markers are associated with cardiac autonomic dysfunction in recent-onset type 2 diabetes

“…Therefore, further studies should address the directionality of these associations and whether both risk factors act additively or even synergistically in the development of macrovascular complications. These studies should not be limited to individuals with diabetes, because the prevalence of CAN may be increased in those with prediabetes 30. Given that both alterations of HRV and subclinical inflammation are modifiable risk factors responding to lifestyle-based and pharmacological interventions,2 a better understanding of the associations reported here might help to better understand and reduce cardiovascular risk in individuals with type 2 diabetes.…”

Structured lifestyle intervention in patients with the metabolic syndrome mitigates oxidative stress but fails to improve measures of cardiovascular autonomic neuropathy

“…Changes in HRV consistent with CAN have been identified at the time of diagnosis in subjects with type 2 diabetes (12; 13), and in patients with impaired glucose tolerance, insulin resistance, and/or the metabolic syndrome (9; 14; 15). These suggest that such impairment may be present either after a relatively brief exposure to sustained hyperglycemia, or develop in conjunction with obesity, insulin resistance and/or intermittent episodes of milder glucose elevations (12; 15). Cross-sectional studies in adults without diabetes provide evidence that indices of CAN are inversely associated with central obesity, insulin resistance, and fasting glucose (9; 14; 15), all components of the MetS.…”

“…These suggest that such impairment may be present either after a relatively brief exposure to sustained hyperglycemia, or develop in conjunction with obesity, insulin resistance and/or intermittent episodes of milder glucose elevations (12; 15). Cross-sectional studies in adults without diabetes provide evidence that indices of CAN are inversely associated with central obesity, insulin resistance, and fasting glucose (9; 14; 15), all components of the MetS. Clustering of major CVD risk factors that includes IFG or IGT, along with low high-density lipoprotein (HDL) cholesterol, elevated triglycerides, elevated blood pressure (BP) and central adiposity are the key features of MetS (16).…”

Entropy Analysis of Short-Term Heartbeat Interval Time Series during Regular Walking

“…Reduced heart rate variability (HRV), a sign of impaired cardiovascular autonomic control [1], has been associated with elevated risk for cardiovascular disease in the general population [2][3][4], and increased mortality in patients with various circulatory system diseases [5][6][7][8]. HRV, by definition, indicates the tiny fluctuations of the time intervals between consecutive normal sinus heartbeats.…”