Inspired by the overwhelming need for PA intervention strategies targeting persons with prediabetes, and the current state of prediabetes and T2D prevalence, the PRE-PAID project set out to build upon the existing body of literature regarding the identification of persons at high risk for developing T2D and utilize both community-based and laboratory-based PA strategies that, in some cases were culturally- specific with the goal of preventing or delaying the onset of T2D.
At the onset of the project, a strategy was developed and enhanced through effective working relationships with various community partners to implement the Phase I screening and recruitment initiative. During this time, the PRE-PAID risk questionnaire and point-of-care blood testing were effectively deployed as a risk assessment tool reaching a broad catchment of participants largely from the targeted, high-risk ethnicities. These participants then were engaged in community-based PA sessions designed to help them accumulate the recommended 150 minutes per week of moderate intensity PA. The sessions were delivered by QEPs assisted by culturally-matched PA leaders and held at venues which were conveniently situated within the target communities involved. The classes were free of charge and provided services such as child minding in an attempt to alleviate as many barriers to PA as possible with hopes of maximizing attendance and adherence to the program.
During the final phase of the project, a more controlled, laboratory-based approach was adopted to examine the effects of two different randomly assigned modes of aerobic training coupled with resistance training on their ability to induce improvements in glycemic control in a population of persons with prediabetes. This type of approach provided an opportunity for enhanced PA supervision and participant adherence/retention. Enhancing the understanding of how different forms of exercise impact glycemic control in prediabetics is vital to the design and implementation of future prevention strategies as well as the development of public health policies and PA recommendations made by various governing bodies.
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Considering the entire body of work described in this thesis it is abundantly clear that the findings from the PRE-PAID project will contribute positively to the field and inform further research initiatives involving persons at high risk for T2D involving PA and/or exercise interventions both at the community level and in a standard exercise environment. If the goals of the project are revisited, it is clear that the community-based screening protocol was able to successfully identify individuals at high risk for developing T2D. The risk questionnaire, coupled with point-of-care blood testing for A1C should be considered as a tool for qualified health professionals and diabetes educators to be used during initial contact with prospective patients/clientele. This approach to screening is relatively cost efficient and portable allowing large catchments of individuals to be assessed with enhanced convenience for those being screened. Prior to engagement in any form of intervention, the first step to prevention of T2D is recognition of risk.
The second objective of the project was to prevent persons with prediabetes from progressing toward T2D by engaging those identified during the screening process in a supervised PA program that is
culturally-specific, community-based and supervised by a QEP. During Phase II, this goal was met largely as a result of collaboration with various community partners. That said, there was a great deal of participant attrition at various stages of Phase II. First, there was a significant drop (32%) in participant number between the initial screening visit and participation in at least one PA class. This occurrence can possibly be explained by the additional time commitment and travel required to attend the classes. In general, the screening sessions provided a convenient opportunity for persons to get screened and only took approximately 15 minutes. The PA classes were on a fixed schedule and required a 60 minute time commitment or more. It is also possible that several participants simply do not see the value of PA participation or fully understand the potential health consequences of T2D. There were also a large number of participants who, even though they participated in one PA session, decided not to attend regularly or provide follow-up measures. Once again, these participants may have been steered away from the intervention given the regular time commitment. Despite the attrition observed, significant
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improvements were observed in A1C, HOMA-β, and strength and aerobic fitness among participants who did provide follow-up measures.
In the final phase of the project, the goal was to determine if differences exist between different forms of exercise in their ability to elicit changes in glycemic control among prediabetic participants. This was accomplished through a randomized, laboratory-based study design. After participation in 3 months of either HIIT or continuous moderated intensity aerobic exercise, no significant differences were observed between the two intervention groups. All participants completed the same resistance training protocol in addition to their randomly assigned aerobic component and mean improvements were observed after 3 months in terms of glycemic control, body composition and physical fitness when analyzed as one group. It is possible that participation exceeding 3 months may elicit differences between the two protocols.
It is also important to note that there were no reported adverse events during any of the community- based PA sessions or the laboratory-based sessions beyond mild muscular discomfort which would be expected during any type of PA intervention involving persons who were previously sedentary. This reaffirms the notion that participation in habitual exercise that is of moderate intensity, or greater, can be performed safely in prediabetic populations. The observed lack of adverse events is attributable, in part, to the presence and training of the QEPs involved in the project. Their strong academic and practical
background provided the necessary tools to administer and progress the participants in a safe and effective manner.
The observed improvements in glycemic control, body composition and physical fitness in Phases II and III substantiate the existing evidence for PA participation. Improvements in these traits have been previously shown to reduce risk for comorbid conditions such as hypertension and CVD. The mechanism through which glycemic control was improved was not a primary goal of this investigation, however, several possible explanations could account for the observed improvements in Phase II and Phase III. Insulin sensitivity has been shown to improve with participation in habitual PA through various
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mechanisms both at the hormonal level and at the level of the muscle. Also, the observed improvements in HOMA-β in both phases indicates an improvement in beta cell function and, coupled with the observed reductions in A1C, add to the ability to conclude that an improvement in glycemic control has taken place.
Despite there being three distinct phases of the PRE-PAID project, each of the phases are closely linked to the importance of prediabetes as an area of focus for both community-based and laboratory- based interventions. The emphasis on prediabetes, specifically, is a deviation from typical health care practices which are predominantly treatment/management based for persons already diagnosed with T2D. If persons with prediabetes are identified and given the opportunity to participate in interventions that will prevent or delay T2D, the devastating complications and associated health care costs of diabetes could be mitigated.