LITERATURE REVIEW AND CRITICAL APPRAISAL 2
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563samplepaper4final1.docxRunning head: LITERATURE REVIEW AND CRITICAL APPRAISAL 1
LITERATURE REVIEW AND CRITICAL APPRAISAL 6
Literature Review and Critical Appraisal
United States University: MSN 563
Dr. Anita Hunter, Ph.D., MSN, RN
STUDENT NAME
August 12, 2020
Literature Review and Critical Appraisal
This paper aims to review five different articles related to the PICOT question: In adults with Type 2 Diabetes (P), how do moderate physical activity at least three times per week (I) compare to a modified diet and moderate physical activity at least three times per week (C) affect HbA1c levels (O) after 16 weeks (T)? This PICOT question is taken from the approved list of subjects appearing on the United States University Approved List for Capstone Projects. Key terms used in this search were "diet", "calories reduced diet", "low carbohydrate diet", "moderate carbohydrate diet", "exercise", "aerobics", "moderate physical activity", "Type 2 Diabetes", "HbA1c", "A1c", "controlling HbA1c", "lowering HbA1c", "diet and HbA1c levels", "exercise and HbA1c levels", "social determinants of health", and "access to healthcare". The search engines used were PubMed, CINHAL Complete, ProQuest Nursing, and Allied Health Source, and Google Scholar. All search engines were accessed through the United States University Library. Boolean operators such as "and" and "or" were used to broaden or define research where needed.
Summaries of Literature
In a systematic review entitled "Clinical Outcomes and Glycaemic Responses to Different Aerobic Exercise Training Intensities in Type 2 Diabetes", 27 randomized control trials with a total of 1372 participants were evaluated for their results (Grace, Chan, Giallauria, Graham & Smart, 2017). The study was published in Cardiovascular Diabetology and included adults over the age of 18 and lasted two weeks. Included were 737 exercise groups and 636 control groups. This review evaluated exercise intensity on the control of HbA1c levels. The study discusses the benefits of lifestyle modification, namely diet and exercise, as beneficial to those with Type 2 Diabetes and HbA1c control. The focus, however, is on exercise intensity. It was discovered that various modalities of exercise result in different effects on HbA1c levels. Combining aerobic activity and resistance training is superior at controlling blood glucose levels for those with T2DM according to this article (Grace et al., 2017). For example, it was discovered that one 4-minute session of High-Intensity Interval Training (HIIT) was not as effective as four 4-minute sessions on HbA1c levels. However, according to this study, moderate exercise is still considered preferable as clinical improvements are seen at a moderate intensity and can be performed by most people (Grace et al., 2017). The primary outcome data in all RCTs were HbA1c levels. The instruments of measurement were HbA1c levels, fasting blood glucose, and weight loss validating the results (Grace et al., 2017).
The strengths of this article include a clear review of studies and benefits supporting a moderate exercise program. Additionally, the number of randomized control trials (RCTs) and participants provides for a detailed analysis. The study points out a weakness in findings related to exercise and red blood cells. Exercise increases red blood cells, and red blood cell lifespan is approximately four months in length. As this study points out, research on the impact of physical activity on HbA1c levels should last a minimum of four months to coincide with the red blood cell lifespan. HbA1C levels are a twelve-week look at plasma glucose concentration. Other parameters for testing should be included for a closer look at exercise related to blood glucose levels in the long run. The studies in this review lasted six weeks or longer, with the highest amount of time being twelve weeks or less (Grace et al., 2017). All findings were consistent and support exercise as a viable means for controlling blood glucose levels. Also, the longer the study continued, the more significant the impact on HbA1c levels. This supports testing subjects with elevated HbA1c levels in exercise programs for longer than twelve weeks (Grace et al., 2017). The more significant analysis could be obtained with a longer duration of studies related to exercise and HbA1c control.
The next study in these summaries, another systematic review, is entitled "The Interpretation and Effect of a Low-Carbohydrate Diet in the Management of Type 2 Diabetes" and was published in The European Journal of Clinical Nutrition (Huntriss, Campbell & Bedwell, 2018). Eighteen studies were included in this review, with a total of 2204 participants that were 18 years of age and older. Seven of the studies analyzed HbA1c levels at three months, eight studies analyzed HbA1c levels at six months, and ten studies analyzed HbA1c levels at one year. At the trial ends, HbA1c was analyzed, and data were available from seventeen studies. Not all studies included could effectively be blinded as participants could evaluate the diet they were to follow. A moderate carbohydrate diet resulted in twelve of the seventeen studies reporting a decrease in HbA1c levels, while four studies reported no change. One study reported the same effects as the control group and favored not reducing carbohydrate intake. The primary outcome data in the RCTs reviewed was HbA1c levels (Huntriss et al., 2018).
Shortcomings of the study were trials having different definitions of low carbohydrate. Some studies used a very low carb diet of fewer than 50 grams of carbohydrates per day. Other studies that considered their diet low or moderate in carbohydrates came in at 120 grams of carbohydrates per day. Adherence to diet was low, particularly in the groups that consumed 50 grams of carbohydrate per day. Several participants and RCTs reviewed add strength to this review, but the conclusion was less than helpful. While there is some evidence that a lower carbohydrate diet can positively impact HbA1c levels, it was considered inconclusive overall, with further studies needed (Huntriss et al., 2018).
The next systematic review in these summaries is entitled "Resistance Exercise Intensity is Correlated with Attenuation of HbA1c and Insulin in Patients with Type 2 Diabetes." The study was published in The International Journal of Environmental Research and Public Health (Liu, Ye, Chen, Zhang, Kuo & Korivi, 2019). There were twenty-four articles and 962 participants included in this review. Of the participants involved, 491 were in the exercise group, and 471 were in the control group. Groups were categorized as the low-moderate intensity in resistance training or high-intensity resistance training. There was also a control group that did not take part in resistance exercise. The report discusses the importance of comparing resistance training to aerobic activity in that aerobic activity can be difficult for overweight or obese individuals (Liu et al., 2019).
Performing resistance exercises can be more comfortable for those with mobility issues and can be done in-home making it convenient. Results revealed that those participating in low-moderate intensity resistance training only experienced a moderate decrease in insulin levels. The groups that performed high-intensity resistance training had significant reductions in insulin levels. However, low-moderate and high-intensity resistance training substantially lowered HbA1c levels, with the most significant lowering seen in the high-intensity group. The primary measurement outcome of this study was HbA1c levels. The report concludes that high-intensity resistance training improves insulin resistance very effectively and lowers HbA1c levels and is more beneficial than aerobic exercise at managing T2DM (Liu et al., 2019).
The strengths of this study are the vast number of RCTs and participants reviewed. Additionally, it is one of the only studies done that compare the effects of resistance training on those with T2DM to aerobic activity with definitive results. This study's weaknesses lie in the lack of timeframes of the RCTs included (Liu et al., 2019).
The systematic review entitled "Exercise Training Modalities in Patients with Type 2 Diabetes Mellitus" was published in The International Journal of Behavioral Nutrition and Physical Activity (Pan et al., 2018). This review included 37 studies and 2208 participants with T2DM. This study evaluated literature that compared the aerobic activity to resistance exercise and a combination of both. The primary measurement of outcome in this study was HbA1c levels, with blood lipids and weight loss being second and third. The study further compared supervised exercise with unsupervised exercise. The findings were that supervised exercise, whether aerobic or resistance, had little improvement over unsupervised activity when it came to HbA1c levels. The study did reveal that the combination of resistance exercise and aerobic exercise yields the most considerable decrease in HbA1c levels. "Compared with the non-diabetic population, the population with T2DM is associated with a higher risk of cardiovascular disease" (Pan et al., 2018). Other markers were measured with the different exercise groups due to the correlation between T2DM and cardiovascular disease. Increase insulin sensitivity as a result of aerobic activity improves lipid profiles, and aerobic activity appears to be more beneficial at lowering LDL cholesterol than resistance activity.
Some scales of measurements, such as quality of life, did not have the same baseline in the RCTs included in the study. Additionally, the duration of exercise sessions and the duration of the length of studies were not included weakening the overall conclusion. This study's strengths are the breakdown of aerobic exercise, strength training, and a combination of activity and their respective impact on HbA1c levels (Pan et al., 2018).
The final systematic review is entitled "Behaviour Change Techniques Targeting Both Diet and Physical Activity in Type 2 Diabetes" and was published in The International Journal of Behavioral Nutrition and Physical Activity (Cradock, ÓLaighin, Finucane, Gainforth, Quinlan, & Ginis, 2017). The review does not compare the effectiveness of diet to an exercise program to control HbA1c levels. Instead, it discusses the use of both diet and exercise together. Thirteen RCTs and evaluations made at three, six, nine, twelve, and twenty-four months. Participants were all adults with T2DM. The primary measurement outcome in this study was HbA1c levels, with weight being secondary. Low carbohydrate or a Mediterranean diet was used in combination with exercise. The review discusses the difficultly in modifying more than one behavior at a time. However, the results are that combining training with diet is a superior approach to controlling HbA1c levels. Behavior change techniques (BCTs) were evaluated, and it was concluded that BCTs outside of diet and exercise do not have much impact on HbA1c levels. It was also found that HbA1c levels improved at the three- and six-month mark, but not sustained after that time (Cradock et al., 2017).
The strengths of this review are the RCTs used and the evaluation of both diet and exercise being used to improve HbA1c levels and the length of the study spanning twenty-four months. The weakness in this review is the difficulty in understanding how many participants were part of the RCTs used. It is also unclear how many participants followed a low carbohydrate diet and how many followed a Mediterranean diet. Diet and exercise combined have the most positive impact on controlling HbA1c levels (Cradock et al., 2017).
Summary of Review
Three systematic reviews regarding the impact of physical activity on HbA1c levels in those with T2DM were summarized. Two systematic reviews related to the effects of diet on HbA1c levels were summarized. All five of the studies were systematic reviews placing them at the top of the evidence pyramid. The objective of this paper related to the PICOT questions was to determine if exercise alone has as much impact on HbA1c levels as the combination of diet and exercise. The results that can be concluded are that diet and exercise combined appear the be the best approach.
The first systematic review of exercise revealed a 0.71% decrease in HbA1c levels with moderate exercise and a 1.03% decrease in HbA1c with intense exercise performed at peak levels (Grace et al., 2017). The second systematic review of activity revealed that low-moderate intensity resistance exercise resulted in a 0.23% decrease in HbA1c levels while the high-intensity group experienced a 0.61% decrease in HbA1c levels (Liu et al., 2019). The third systematic review of exercise control of HbA1c levels revealed that aerobic exercise compared to resistance exercise programs resulted in a 0.30% decrease in HbA1c levels, whether the plans were supervised or unsupervised. Combined exercise resulted in a 0.47% decrease in HbA1c levels (Pan et al., 2018).
The first systematic review approaching HbA1c control with diet was related to a low carbohydrate diet. The low carbohydrate diet resulted in a decrease in HbA1c levels of 0.28%, whether participants consumed 50 grams or 120 grams of carbohydrates per day (Huntriss et al., 2018). The second article address diet and exercise combined. Though it was unclear who was following the low carbohydrate diet and who was following the Mediterranean diet, the first three months resulted in a decrease of 1.11% HbA1c. After six months, the reduction in HbA1c levels was 0.67%. At the end of the twenty-four-month analysis, the reduction in HbA1c levels was 0.53% (Cradock et al., 2017).
The most substantial decrease in HbA1c was realized in the first three months of diet and exercise combined. The next highest reduction of HbA1c levels was with intense exercise, followed by moderate exercise. This data indicates that activity is vital to controlling HbA1c levels with diet having an impact on those levels. Higher intensity exercise is more effective at reducing HbA1c levels. For those who cannot perform high-intensity aerobics, a program of resistance training can be beneficial.
There are very few studies that evaluate exercise alone compared with exercise and diet to manage blood glucose levels in those with T2DM. The lack of studies regarding diet and exercise and the impact on HbA1c levels could be expanded on. Additionally, there is a lot of leaning toward a low carbohydrate diet to control HbA1c levels when there may be diets more suited to blood sugar control. While some articles addressed different diets, it was not cost-effective to purchase them for this review.
References
Cradock, K. A., ÓLaighin, G., Finucane, F. M., Gainforth, H. L., Quinlan, L. R., & Ginis, K. A. (2017). Behaviour change techniques targeting both diet and physical activity in type 2 diabetes: A systematic review and meta-analysis. The International Journal of Behavioral Nutrition and Physical Activity, 14(1), 18. https://doi.org/10.1186/s12966-016-0436-0
Grace, A., Chan, E., Giallauria, F., Graham, P., & Smart, N. (2017). Clinical outcomes and glycaemic responses to different aerobic exercise training intensities in type II diabetes: a systematic review and meta-analysis. Cardiovascular Diabetology, 16, 37. https://doi.org/10.1186/s12933-017-0518-6.
Liu, Y., Ye, W., Chen, Q., Zhang, Y., Kuo, C., & Korivi, M. (2019). Resistance exercise intensity is correlated with attenuation of hba1c and insulin in patients with type 2 diabetes: a systematic review and meta-analysis. The International Journal of Environmental Research and Public Health. https://doi.org/10.3390/ijerph16010140
Pan, B., Ge, L., Xun, Y. Q., Chen, Y. J., Gao, C. Y., Han, X., Zuo, L. Q., Shan, H. Q., Yang, K. H., Ding, G. W., & Tian, J. H. (2018). Exercise training modalities in patients with type 2 diabetes mellitus: a systematic review and network meta-analysis. The International Journal of Behavioral Nutrition and Physical Activity, 15(1), 72. https://doi.org/10.1186/s12966-018-0703-3.
