The study covered in this summary is a preprint and has not yet been peer reviewed.

Key Takeaways

• The results document a strong, inverse relationship between cardiorespiratory fitness and new-onset type 2 diabetes in a study of more than 8700 people from Saudi Arabia.

• The rate of incident diabetes fell by a significant 10% for each 1 unit increase in baseline level of metabolic equivalents of task (METs), a measure of cardiorespiratory fitness, in an analysis that adjusted for potential confounders.

• This inverse relationship between increased cardiorespiratory fitness and a reduced incidence of diabetes was independent of other traditional risk factors for diabetes.

Why This Matters

• The findings add to existing evidence for the benefits of higher overall fitness and suggest that maintaining a high cardiorespiratory fitness level may help prevent type 2 diabetes.

• The authors hope their findings encourage health professionals to advise the general public, as well as people with diabetes, to have an active lifestyle and to improve their fitness.

Study Design

• This retrospective, observational, cohort study included 8722 consecutive people with no diagnosis of diabetes assessed with clinically indicated exercise treadmill stress testing from April 2001 to December 2016 at the King Abdulaziz Cardiac Center in Riyadh, Saudi Arabia. 

• Patients underwent symptom-limited maximal treadmill stress testing that followed the standard Bruce protocol.

• Researchers converted the stress test results into METs to quantify cardiorespiratory fitness based on the maximal speed and grade achieved during total treadmill time.

Key Results

• A multivariate Cox regression model that adjusted for potential confounders showed a significant 10% reduction in the risk of incident diabetes with each incremental unit increase in baseline METs.

• Adding METs to the analysis increased the ability of the model to account for episodes of incident diabetes (the C-statistic; the area under the receiver operating characteristic curve) from 62% in the baseline model to 68%, a significant increase.  

• During a median follow-up of 5.2 years, 2280 participants (26%) developed new-onset type 2 diabetes.

• Participants were an average of 46 years old, two thirds were men, a third had hypertension, 28% had hyperlipidemia; 5% had prior coronary artery disease and less than 1% had heart failure

Limitations

• Cardiovascular health is independently associated with behaviors that may contribute to fitness, but the researchers were not able to formally assess these behaviors.

• Identification of people with incident diabetes depended on medical records that did not include systematic measurements of A1c, blood glucose, or oral glucose tolerance, and therefore the study may have included some people with undiagnosed diabetes or missed some cases of incident diabetes.

• The study population was composed of people referred for stress testing. These people likely had a higher prevalence of cardiovascular disease at baseline than the general population, which may have led to a referral bias that limits generalizability of the study.

• The study was observational, with covariates assessed by information in medical records rather than by direct measurement, which could result in residual confounding despite adjustment.

• The study ran at a single center, and although the study cohort was diverse, it may not represent the adult population of Saudi Arabia or other countries.

Disclosures

• The study received no outside funding.

• None of the authors had disclosures.

This is a summary of the preprint study, “Prognostic Value of Exercise Capacity In Incidence Diabetes: A Country With High Prevalence of Diabetes,” written by researchers at the King Abdulaziz Medical City in Riyadh, Saudi Arabia, available on Research Square, and provided to you by Medscape. This study has not yet been peer reviewed. The full text is available on researchsquare.com.

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