THE EFFECTS OF AEROBIC EXERCISE ON TYPE-II DIABETES HOW EXERCISE CAN SAVE YOUR LIFE

Sydney Greene

Over 37 million Americans suffer from diabetes mellitus, commonly referred to as diabetes. More than 90% of these cases are type-II diabetes (Centers for Disease Control and Prevention, 2021). Diabetes mellitus is a metabolic disorder that results from the inability of the pancreas to produce adequate amounts of insulin, eventually resulting in the inability of the individual to properly regulate their own blood sugar naturally. This has become an issue of greater concern as rates of obesity and insulin-dependent individuals have increased in recent years. The prevalence of this issue has been compounded by the amount of misinformation and conflicting recommendations that are readily found on the internet. This previous summer, I had a research internship with Dr. Kashif Latif of the AM Diabetes & Endocrinology Center as he began conducting a study of Medicare patients (ages 65+) with type-II diabetes who were involved in their on-site aerobic exercise classes. This study aims to collect data on patients who consistently attend these exercise classes to determine whether aerobic exercise has a significant effect on their treatment and management of type-II diabetes in patients 65 years old and older.

To fully understand the implications of this study, it is important to note the distinction between type-I and type-II diabetes, and why no patients with type-I were not considered as study subjects. Type-II diabetes differs from type-I diabetes in both cause and treatment. Type-I diabetes is caused by an autoimmune response in which the body attacks its own insulin-producing beta cells in the pancreas. This often results in the complete inability of the individual to produce their own metabolically useful insulin. On the other hand, type-II diabetes can be prevented and is often caused by prolonged obesity and high blood sugar that increases insulin resistance. In this case, the pancreas is still successfully producing insulin, but the insulin receptors on the surface of cells that regulate glucose uptake/release become insulin resistant and are not as responsive to the same levels of insulin. Over time, this can result in pancreatic fatigue from having to produce greater and greater amounts of insulin to regulate blood glucose levels. As far as differences in disease management, type-I is typically treated with blood sugar monitoring and injections of synthetic insulin, whereas type-II is usually managed with improvements in diet, more exercise, and diabetes medications aimed at lowering blood glucose levels and improving insulin sensitivity (Mayo Foundation for Medical Education and Research, 2022).

Another key aspect of this study that may not be as widely known is the impact of muscle composition on the management of diabetes. Normal (non-diabetic) human muscle tissue is composed of equal amounts of type 1 and type 2 muscle fibers. Type 1 fibers, commonly referred to as “slow-twitch” fibers, require oxygen in order to properly function. In an oxygen-rich environment, type 1 muscle fibers can undergo oxidative phosphorylation, a process necessary to produce ATP, the currency of cellular energy (Talbot, J., & Maves, L., 2016). When there are more type 1 muscle fibers present, individuals have better endurance, better insulin responsiveness of the cells in the muscle tissue, and higher utilization of oxygen during exercise (Stuart, C.A., et al., 2013). Type 2 muscle fibers, commonly referred to as “fast-twitch” fibers, can be subdivided into mixed type 2a and mixed type 2x fibers. Type 2a fibers can switch between aerobic (oxygen rich) and anaerobic (oxygen deficient) ATP production (Talbot, J., & Maves, L., 2016). In a study that was conducted by the Quillen College of Medicine of East Tennessee State University, it was found that this muscle fiber type fatigued quicker than type 1 fibers due to less efficient glycolysis and ATP production, and contributed to less whole-body fat oxidation. It also appeared that there are fewer IRS-1 receptors and GLUT4 proteins (vital cellular structures responsible for insulin sensitivity and glucose uptake) in type 1 muscle tissue. Subjects with type-II diabetes had more than a two-fold increase in mixed type 2a muscle fibers (Stuart, C.A., et al., 2013). This means that patients with type-II diabetes have less available tissue to facilitate these key insulin pathway actions. The proportion of type 1 muscle fibers is also negatively correlated with age, meaning that individuals with type-II diabetes who are older will have an increasingly difficult time managing their diabetes and type 1 muscle fiber composition (Stuart, C.A., et al., 2013).

As previously mentioned, most Americans who live with diabetes mellitus have the type-II delineation. Historically, allopathic disease management methods focused on treatment of the disease and any comorbidities after they become a concern rather than focusing on the prevention of complications. This study will enable the understanding of whether consistent aerobic exercise improves the ability of an older population of patients to manage their type-II diabetes. If aerobic exercise is found to improve patients’ ability to manage their diabetes, then new avenues of preventative treatments that reduce comorbidities and improve overall quality of life can be established.

To begin this study, a comprehensive database to organize patient information had to be designated. Though several options and formats were considered, an Excel workbook was selected to organize the data due to the platforms’ simplicity, accessibility, and data organization/ analysis capabilities. Then, metrics were chosen that would be monitored and analyzed to determine the outcome of the study. These metrics had to be directly indicative of the status of the patient’s diabetes management. We therefore selected metrics indicative of overall health, as well as metrics more specific to diabetes. The metrics we selected were BMI (body mass index), blood pressure, pulse, weight, A1C, and blood glucose levels. Values for these data points were collected for each patient during their regularly scheduled visits to the clinic. Baseline values for each of these points were recorded in the database for each patient using the metrics collected at their visit closest to their start time of the program. All subsequent values for each metric from visits after the date of the baseline visit were placed in the database and will continue in this fashion until the end of the study. Due to the policy of the clinic, visits for diabetes patients occur approximately every three months, enabling consistent data collection from each patient for the duration of the study.

To draw a generalizable conclusion applicable for the large population of people living with type-II diabetes, many subjects need to be involved in the study and their metrics will need to be collected over a long period of time. Though it is currently too early to draw any conclusions, the current data trends look promising. The status of this study is ongoing and will continue for the foreseeable future until there is a statistically significant number of patients and data points to draw a general conclusion.

Hopefully, the results of this study will show that consistent aerobic exercise improves the disease management and quality of life of people with typeII diabetes. Once the study is complete, the findings can be used to help patients make educated decisions about their disease management, help prevent future diabetes related complications and make effective holistic health care more accessible to more people.

References:

Centers for Disease Control and Prevention. (2021, December 16). Type 2 diabetes. Centers for Disease Control and Prevention. Retrieved December 12, 2022, from https://www.cdc.gov/diabetes/basics/type2. html#:~:text=Healthy%20eating%20is%20your%20recipe,adults%20 are%20also%20developing%20it.

Mayo Foundation for Medical Education and Research. (2022, November 19). Type 2 diabetes. Mayo Clinic. Retrieved December 12, 2022, from https://www.mayoclinic.org/diseases-conditions/type-2-diabetes/ diagnosis-treatment/drc-20351199

Stuart, C.A., McCurry, M.P., Marino, A., South, M.A., Howell, M.E., Layne, A.S.et al. (2013) Slow-twitch fiber proportion in skeletal muscle correlates with insulin responsiveness. J. Clin. Endocrinol. Metab. 98, 2027–2036 10.1210/jc.2012-3876

Talbot, J., & Maves, L. (2016). Skeletal muscle fiber type: using insights from muscle developmental biology to dissect targets for susceptibility and resistance to muscle disease. Wiley interdisciplinary reviews.

Developmental biology, 5 (4), 518–534. https://doi.org/10.1002/wdev.230