Abnormal response to exercise in middle-aged NIDDM patients with and without autonomic neuropathy

Correlation between impaired hemodynamic response and cardiopulmonary fitness in middle-aged type 2 diabetes mellitus patients: a case-control study

PURPOSE

Impaired cardiorespiratory fitness (CRF) is a predictor of mortality in patients with type 2 diabetes mellitus (T2DM). It is still not known how the exercise hemodynamic response correlates with CRF. The purpose was to assess the correlation between hemodynamic changes and CRF in middle-aged patients with T2DM.

METHODS

After 1:1 matching by age and sex, 139 T2DM patients and 139 non-T2DM controls who completed the exercise treadmill test were included. Maximal aerobic capacity (VO_2max), exercise-induced changes in heart rate (ΔHR), systolic blood pressure (ΔSBP), diastolic blood pressure (ΔDBP), and rate-pressure product (ΔRPP) were measured. HRR₁ was calculated as the maximum heart rate minus the heart rate after 1 min of rest.

RESULTS

Compared to the control population, T2DM patients had decreased ΔHR (87 (77, 97) v 93 (84, 104) bpm, p < 0.05), ΔRPP (3833.64 ± 1670.34 v 4381.16 ± 1587.78 bpm∙mmHg, p < 0.05), HRR₁ (21 (14, 27) v 21 (17, 27) bpm, p < 0.05), and VO_2max (32.76 ± 5.63 v 34.68 ± 5.70 ml/kg/min, p < 0.05). Multiple linear regression analysis showed that ΔHR and HRR₁, yielded a positive correlation with VO_2max in T2DM patients (β = 0.325, P < 0.001; β = 0.173, P = 0.01).

CONCLUSION

The presence of impaired hemodynamic response and VO_2max in middle-aged T2DM patients and the association of impaired ΔHR, HRR₁, and VO_2max may indicate a physiological pathway of impaired CRF, and our results support the need for cardiorespiratory screening and individualized treatment of middle-aged T2DM patients.

Artificial Intelligence (AI) approach to identifying factors that determine systolic blood pressure in type 2 diabetes (study from the LOOK AHEAD cohort)

BACKGROUND AND AIMS

Artificial Intelligence (AI) methods have recently become critical for research in diabetes in the era of big-data science.

METHODS

In this study, we used the data from the LOOK AHEAD and applied Random Forest to examine the factors determining SBP in persons with diabetes using the software R (version 4.0.3).

RESULTS

Our analysis (that included 4723 participants) showed that maximal exercise capacity, age, albumin to creatinine ratio, and serum creatinine were the key variables that determined systolic blood pressure.

CONCLUSIONS

Maximum exercise capacity is an important predictor of systolic blood pressure in patients with type 2 diabetes.

Blunted heart rate response to upright tilt in people with Down syndrome

OBJECTIVES

To determine whether heart rate and blood pressure responses to upright tilt would be lower in subjects with Down syndrome (DS) than in control subjects with no disabilities.

DESIGN

Comparative study.

SETTING

University research laboratory.

PARTICIPANTS

Nineteen people with DS (mean age, 25.1+/-7.3 y) and 17 control subjects without disabilities (mean age, 28.4+/-5.6 y).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Heart rate and blood pressure recordings were obtained at rest and during a 2-minute period of passive head up tilt to 80 degrees .

RESULTS

Heart rate and blood pressure increased significantly during the first 30 seconds of upright tilt in both groups ( P <.05) and then stabilized for the remainder of the test. The initial heart rate response to head up tilt (first 30s) was significantly higher in controls compared with subjects with DS ( P <.05), whereas the blood pressure response did not differ between groups ( P >.05). Controlling for heart rate reserve showed a blunted heart rate response through the tilt period in subjects with DS.

CONCLUSIONS

These data show a blunted heart rate response to upright tilt in people with DS, despite similar changes in blood pressure, consistent with reduced sympathoexcitation and possibly altered baroreceptor function in these people with DS.

Evaluation of physical fitness in patients with Type 2 diabetes mellitus

PURPOSE

The aim of this study was to compare functional capacity in 30 Type 2 Diabetic patients with 30 healthy non-diabetic control subjects.

METHODS

Physical fitness was evaluated using the "EUROFIT Physical Fitness Test Battery". This battery estimates body composition, cardiopulmonary, musculoskeletal and motor fitness.

RESULTS

Percentage of body fat (PBF) was higher in the diabetic compared with control groups (P<0.05) although body mass index (BMI) was similar. Biceps and suprailiac skinfold thickness were also greater in the diabetic group (P<0.05). The 6-min walking distance and VO(2max) were significantly lower in the diabetic group (P<0.05). The diabetic patients had lower values of the single leg balance test with eyes opened and closed. Jump-stretch, handgrip and side-bending of trunk tests were also lower in the diabetic patients.

CONCLUSION

Physical functional capacity is lower in Type 2 diabetic patients than in age-matched control subjects.

Use of heart rate reserve and rating of perceived exertion to prescribe exercise intensity in diabetic autonomic neuropathy

OBJECTIVE

Individuals with diabetic autonomic neuropathy (DAN) exhibit an increased resting heart rate but depressed maximal heart rate. Thus, the purpose of this study was to examine the validity of using either percent of heart rate reserve (HRR) or a rating of perceived exertion (RPE) scale to prescribe exercise intensity in diabetic individuals both with and without DAN.

RESEARCH DESIGN AND METHODS

The subjects consisted of 23 individuals with type 2 diabetes, ages 45-75 years, with (DAN; n = 13) or without (No DAN; n = 10) clinical signs of DAN, as assessed by heart rate variability using the expiration-to-inspiration ratio of the R-R interval. Peak aerobic capacity was determined using a graded protocol on a cycle ergometer, with RPE, heart rate, and VO(2) values recorded at each stage.

RESULTS

The subjects were similar with the exception of depressed autonomic function in DAN subjects. Peak respiratory exchange ratio values were significantly higher (P < 0.05) in the DAN group (1.08 +/- 0.02 vs. 1.02 +/- 0.01 in No DAN subjects), although DAN subjects exhibited a significantly lower (P < 0.05) peak exercise heart rate. A similarly highly linear relationship between %HRR and percent VO(2) reserve (VO(2)R) existed for both groups (r = 0.98). A similar slightly weaker relationship (r = 0.94) was found between RPE and %VO(2)R.

CONCLUSIONS

In conclusion, in diabetic individuals, %HRR provides an accurate prediction of %VO(2)R and can be used to prescribe and monitor exercise intensity, regardless of the presence of DAN. The RPE scale is also a valid, albeit slightly less accurate, method to monitor exercise intensity in diabetic individuals.

Impact of left ventricular diastolic dysfunction on maximal treadmill performance in normotensive subjects with well-controlled type 2 diabetes mellitus

Patients with type 2 diabetes often have impaired exercise capacity compared with nondiabetic subjects. Left ventricular (LV) diastolic dysfunction has been shown to limit exercise performance in nondiabetic subjects. Men with well-controlled type 2 diabetes were divided into 2 groups: normal LV diastolic function (group 1, n = 9) or LV diastolic dysfunction (group 2, n = 10) based on standard echocardiographic criteria using pulmonary veins and transmitral flow recordings. They were matched for age and had no evidence of systemic hypertension, macroalbuminuria, coronary artery disease, congestive heart failure, clinical diabetic complications, and thyroid disease. Good metabolic control was demonstrated by glycated hemoglobin levels of 6.7+/-1.6% and 6.6+/-2.5% (means +/- SD) in patients with LV diastolic dysfunction and in controls, respectively. Each subject performed a symptom-limited modified Bruce protocol treadmill exercise test. Maximal treadmill performance was higher in subjects with normal diastolic function compared with subjects with LV diastolic dysfunction when expressed in time (803+/-29 vs. 662+/-44 seconds, respectively, p<0.02) or in METs (11.4+/-1.2 vs. 9.5+/-1.9 METs, respectively, p<0.02). Moreover, there was a correlation between E/A ratio and exercise duration (r = 0.64, p = 0.004) or E/A ratio and METs (r = 0.658, p = 0.003). There were no significant differences in maximal heart rate, maximal systolic and diastolic blood pressure, or maximal rate-pressure product attained during the exercise test. In conclusion, this study demonstrated that LV diastolic dysfunction influences maximal treadmill performance and could explain lower maximal performance observed in patients with type 2 diabetes.