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. 2018 Apr 2;13(4):e0194750.
doi: 10.1371/journal.pone.0194750. eCollection 2018.

Heart rate dynamics during cardio-pulmonary exercise testing are associated with glycemic control in individuals with type 1 diabetes

Othmar Moser  1   2 , Max L Eckstein  1   2 , Olivia McCarthy  1   2 , Rachel Deere  1   2 , Stephen C Bain  1 , Hanne L Haahr  3 , Eric Zijlstra  4 , Tim Heise  4 , Richard M Bracken  1   2
Affiliations

Heart rate dynamics during cardio-pulmonary exercise testing are associated with glycemic control in individuals with type 1 diabetes

Othmar Moser et al. PLoS One. .

Abstract

Introduction: This study investigated the degree and direction (kHR) of the heart rate to performance curve (HRPC) during cardio-pulmonary exercise (CPX) testing and explored the relationship with diabetes markers, anthropometry and exercise physiological markers in type 1 diabetes (T1DM).

Material and methods: Sixty-four people with T1DM (13 females; age: 34 ± 8 years; HbA1c: 7.8 ± 1% (62 ± 13 mmol.mol-1) performed a CPX test until maximum exhaustion. kHR was calculated by a second-degree polynomial representation between post-warm up and maximum power output. Adjusted stepwise linear regression analysis was performed to investigate kHR and its associations. Receiver operating characteristic (ROC) curve was performed based on kHR for groups kHR < 0.20 vs. > 0.20 in relation to HbA1c.

Results: We found significant relationships between kHR and HbA1c (β = -0.70, P < 0.0001), age (β = -0.23, P = 0.03) and duration of diabetes (β = 0.20, P = 0.04). Stepwise linear regression resulted in an overall adjusted R2 of 0.57 (R = 0.79, P < 0.0001). Our data revealed also significant associations between kHR and percentage of heart rate at heart rate turn point from maximum heart rate (β = 0.43, P < 0.0001) and maximum power output relativized to bodyweight (β = 0.44, P = 0.001) (overall adjusted R2 of 0.44 (R = 0.53, P < 0.0001)). ROC curve analysis based on kHR resulted in a HbA1c threshold of 7.9% (62 mmol.mol-1).

Conclusion: Our data demonstrate atypical HRPC during CPX testing that were mainly related to glycemic control in people with T1DM.

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Conflict of interest statement

Competing Interests: O. Moser has received lecture fees from Medtronic, a travel grant from Novo Nordisk A/S and research grants from Sêr Cymru II COFUND fellowship/European Union and Novo Nordisk A/S. M. L. Eckstein has received a KESS2/European Social Fund scholarship. S. C. Bain reports having received honoraria, teaching and research grants from the Abbott, Astra Zeneca, Boehringer Ingelheim, BMS, Diartis, Eli Lily and Company, GlaxoSmithKline, Johnson & Johnson, Merck Sharp & Dohme, Novartis, Novo Nordisk, Pfizer, Roche, Sanofi-Aventis, Schering-Plough, Servier and Takeda. T. Heise reports having received research funds from Adocia, Astra Zeneca, BD, Biocon, Boehringer Ingelheim, Dance Pharmaceuticals, Grünenthal, Eli Lily and Company, Medtronic, Novo Nordisk, Novartis, Sanofi and Senseonics and having received speaker honoraria and travel grants from Eli Lily and Company, Mylan and Novo Nordisk. R. M. Bracken reports having received honoraria, travel and educational grant support from, Boehringer-Ingelheim, Eli Lily and Company, Novo Nordisk, Sanofi-Aventis. E. Zijlstra, R. Deere and O. McCarthy have no disclosures to report. H. L. Haahr is employee and shareholder in Novo Nordisk A/S.

Figures

Fig 1
Fig 1. Schematic of the heart rate to performance curve (HRPC) and detection of the heart rate turn point (HRTP) during CPX testing, illustrating a regular HRPC (A) and an inverted HRPC (B).
The difference in HRPC translates to a lower heart rate at HRTP (HRHRTP) when given as percentage of the maximum heart rate (%HRmax) (difference 10%). kHR = degree and direction of the heart rate to performance curve. HRmax = maximum heart rate.
Fig 2
Fig 2. Consort flow diagram.
Fig 3
Fig 3. Single plots of the association of kHR and HbA1c (A), age (B) and diabetes duration (C).
kHR = degree and direction of the heart rate to performance curve.
Fig 4
Fig 4. Single plots of the association of kHR and HRHRTP at %HRmax (A) and Pmax (B).
kHR = degree and direction of the heart rate to performance curve, HRHRTP at %HRmax = heart rate at the heart rate turn point given as percentages of the maximum heart rate, Pmax = maximum power output relativized to bodyweight.
Fig 5
Fig 5. Receiver operating characteristic (ROC) curve analysis of HbA1c.
The sensitivity is plotted against 100–specificity to indicate accuracy. The optimal value for sensitivity was 81%, which corresponded to a specificity of 82%. This represents a cut off level for HbA1c of 7.9% (63 mmol.mol-1).
See this image and copyright information in PMC

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