Heart rate variability after bariatric surgery: The add-on value of exercise

PURPOSE

To assess the impact of bariatric surgery and an added supervised exercise training programme on heart rate variability (HRV) in patients with severe obesity.

METHODS

Fifty-nine patients who underwent bariatric surgery were randomised in the post-operative period to a 12-week supervised exercise training programme (moderate intensity combination aerobic/resistance exercise training programme) or a control group. Indices of HRV including time-domain, spectral-domain, and nonlinear parameters were measured preoperatively, and at 3, 6, and 12 months.

RESULTS

After the surgical procedure, both groups improved anthropometric parameters. Type 2 diabetes, hypertension, and dyslipidemia resolutions were similar between groups. Total body weight loss at 6 and 12 months were also comparable between groups (6 months: 28 ± 6 vs. 30 ± 6%; 12 months: 38 ± 9 vs. 38 ± 10%; control vs. intervention group respectively). Bariatric surgery improved HRV parameters at 12 months compared to the pre-operative values in the intervention group: standard deviation of R-R interval (SDNN) (156.0 ± 46.4 vs. 122.6 ± 33.1 ms), low frequency (LF) (6.3 ± 0.8 vs. 5.8 ± 0.7 ms²), and high frequency (HF) (5.1 ± 0.8 vs. 4.7 ± 0.9 ms²) (all p<0.001). For the control patients, similar improvements in SDNN (150.0 ± 39.4 vs. 118.8 ± 20.1 ms), LF (6.1 ± 0.9 vs. 5.7 ± 0.8 ms²), and HF (5.0 ± 0.9 vs. 4.7 ± 0.9 ms²) were obtained (all p<0.001). However, there was no add-on impact of the supervised exercise training programme on HRV after 12 months (p>0.05 for all HRV parameters).

CONCLUSION

Bariatric surgery is associated with an improvement in HRV. A supervised exercise training programme in the post-operative period did not modulate further the benefits of bariatric surgery regarding HRV parameters.

Plasma adiponectin concentration is strongly associated with VLDL-TG catabolism in postmenopausal women

BACKGROUND AND AIMS

To investigate associations between plasma adiponectin concentration and very-low density lipoprotein-triglyceride (VLDL-TG) secretion and catabolism in postmenopausal women.

METHODS AND RESULTS

This cross-sectional study included 30 postmenopausal women. Plasma adiponectin concentration was measured by ELISA. Insulin sensitivity was assessed by a 2-h euglycemic-hyperinsulinemic clamp. Fasting plasma glucose (FPG) and 2-hour plasma glucose (2hPG) were measured during an oral glucose tolerance test. The calculation of VLDL-TG fractional catabolic rate (FCR) and VLDL-TG total secretion rate (TSR) were based on the monoexponential decrease of TG-[²H₅] glycerol values obtained following the administration of a ²H₅-glycerol bolus. Plasma adiponectin concentration was negatively associated with VLDL-TG TSR (r=-0.50; p=0.005) and positively associated with VLDL-TG FCR (r=0.54; p<0.002). This latter association remained significant after further adjustments for insulin sensitivity, visceral adipose tissue, HDL-C, FPG and 2hPG concentrations. In a multivariate model including adiponectin, insulin sensitivity and 2hPG, plasma adiponectin level was the strongest correlate of VLDL-TG FCR.

CONCLUSIONS

Elevated plasma adiponectin concentration is associated with a favourable VLDL-TG metabolism.

High normal 2-hour plasma glucose is associated with insulin sensitivity and secretion that may predispose to type 2 diabetes

AIMS/HYPOTHESIS

The aim of this study was to evaluate differences in insulin sensitivity, insulin secretion and risk factors for cardiovascular disease between subjects with a 2-h plasma glucose (2hPG) level within the normal range (NPG) and subjects with IGT, following a 75-g OGTT. We also aimed to determine the respective contributions made by 2hPG and fasting plasma glucose to the metabolic risk profile.

METHODS

We compared cardiovascular risk factors and insulin sensitivity and insulin secretion by using several indices calculated using measurements obtained during an OGTT. Subjects (n=643, age 18-71 years) were participants in the Quebec Family Study and were categorised according to 2hPG as having low NPG (2hPG <5.6 mmol/l, the group median for normal values), high NPG (2hPG 5.6-7.7 mmol/l) or IGT (2hPG 7.8-11.0 mmol/l). Subjects with type 2 diabetes were excluded from all analyses.

RESULTS

Beta cell function and insulin sensitivity progressively decreased with increasing 2hPG. Compared with subjects with low NPG, subjects with high NPG were more insulin-resistant (p<0.05) and had reduced insulin secretion (adjusted for insulin resistance) (p<0.001). They also had higher plasma triglyceride concentrations (p<0.01) and cholesterol:HDL cholesterol ratios (p<0.05). These differences remained even after adjustment for age, sex, BMI and waist circumference. Multivariate analyses showed that 2hPG was closely associated with risk factors for diabetes and with cardiovascular variables, including triglycerides (p<0.0001) and apolipoprotein B (p<0.01).

CONCLUSIONS/INTERPRETATION

These results show that deteriorations in glucose-insulin metabolism, which may predispose individuals to type 2 diabetes and cardiovascular disease, are already present in subjects with 2hPG concentrations within the high normal range. Independently of obesity, 2hPG was found to explain, in part, the variance observed in cardiovascular and diabetes risk factors. In addition, elevated 2hPG was associated with metabolic alterations that appear to be the most detrimental to metabolic health. Thus, 2hPG values within the high normal range may be an important marker for the identification of people at risk of complications related to type 2 diabetes.

Impaired fasting glucose vs. glucose intolerance in pre-menopausal women: distinct metabolic entities and cardiovascular disease risk?

BACKGROUND

Impaired glucose tolerance (IGT) is associated with an increased cardiovascular disease risk. Less is known about cardiovascular disease risk among subjects with impaired fasting glucose (IFG) or with combined IFG and IGT.

AIMS

To compare body composition, body fat distribution, plasma glucose-insulin homeostasis and plasma lipid-lipoprotein profile between pre-menopausal women having either a normal glucose tolerance (NGT), isolated IFG, isolated IGT or combined IFG and IGT.

METHODS

Three hundred and thirty-four women with NGT, 11 women with IFG, 35 women with IGT and 10 women with both IFG and IGT were studied.

RESULTS

Women with IFG were characterized by a higher visceral adipose tissue (AT) accumulation than women with NGT (P < 0.05). Also, they were characterized by a higher subcutaneous AT area and by higher body fat mass than NGT and IGT women (P < 0.05). However, their lipid-lipoprotein profile was comparable with that of NGT women, except for reduced HDL-cholesterol concentrations (P < 0.05). After adjustment for visceral AT, women with IFG had lower total cholesterol, LDL-cholesterol and apolipoprotein B (apoB) levels than the three other groups. They also had lower HDL(2)-cholesterol than NGT women and lower total cholesterol/HDL-cholesterol ratio than IGT women. Women with IGT showed higher triglyceride and apoB concentrations and a higher total cholesterol/HDL-cholesterol ratio than women with NGT (P < 0.05). Overall, women with combined IFG and IGT showed body fatness characteristics and alterations in their metabolic risk profile which were essentially similar to women with isolated IGT.

CONCLUSIONS

These results indicate that there are significant differences in anthropometric and metabolic variables between pre-menopausal women with IFG vs. IGT and that the association between body fatness-body fat distribution indices and the metabolic profile may differ between IFG and IGT women.