Sympathetic Activity and Cardiovascular Risk Markers in Non-diabetic and Diabetic Mexican Older Adults

Abstract

Age-related metabolic dysfunctions occur in a wide variety of clinical manifestations, including hyperglycemia, dyslipidemia and increased body fat. These conditions increase the risk of cardiovascular diseases (CVD), which can develop low heart rate variability (HRV) and higher resting heart rate (HR). The pathological metabolic conditions in older adults are associated with a hyperactive sympathetic nervous system (SNS). PURPOSE: To compare the SNS activity and metabolic markers associated to CVD in type 2 diabetic (T2D) and non-diabetic (ND) Mexican older adults. METHODS: Volunteers were 11 T2D (Age = 60.8 ± 5.2 yr., body mass index [BMI]= 29.9 ± 4.6 kg/m2) and 17 ND (Age = 64 ± 4.8 yr., BMI = 28.4 ± 4.1 kg/m2) older adults residing in Baja California, Mexico. Morning blood serum samples were collected after 8-h fasting following body composition analysis (InBody 770, Cerritos, CA). A 5-min resting ECG recording (BioRadio, Cleveland, OH) was used to analyze HRV. Time and frequency domain analysis were assessed with Kubios HRV 3.1 software (Kubios Oy, Finland). RESULTS: Between-group differences were found on blood glucose (T2D = 171.9±91.6 vs. ND = 80.17±12.0mg/dL, p < 0.001), and triglycerides (T2D = 266.9±126.17 vs. ND = 60.54 ± 47.8mg/dL, p < 0.02). Non-significant between-group differences were found on cholesterol (T2D = 183.0±45.1 vs. ND = 180.9±29.7mg/dL, p = 0.88), HDLc (T2D = 60.54±55.8 vs. ND = 47.88±20.73mg/dL, p = 0.92) and LDLc levels (T2D = 84.4±44.6 vs. ND = 107.84±26.74mg/dL, p = 0.22). The HR (T2D = 72.6±11.5 vs. ND = 71.7±7.8bpm, p = 1.0), beat-to-beat intervals (RR) (T2D = 845.7±128.7 vs. ND = 843.7±93ms, p = 0.94), Root Mean Square of the Successive Differences (RMSSD) (T2D = 68.7±58.0 vs. ND = 45.6±31.2ms, p = 0.45) and relative successive beats with > 50ms of difference (pNN50) (T2D = 23.4±25.5 vs. ND = 9.7±13.7%, p = 0.32) were similar in both groups. High- (T2D = 48.14±24.64 vs. ND = 45.5±22.9n.u., p= 0.67) and Low-frequency (T2D = 51.7±24.5 vs. ND = 54.0±23.3n.u., p= 0.70) time domains and LF/HF ratio (T2D = 2.0±2.4 vs. ND = 2.4±3.0, p = 0.68) were similar in both groups. CONCLUSIONS: Diabetic conditions did not affect substantially SNS activity compared with non-diabetic condition in a sample of Mexican older adults.