Exercise as it relates to Disease/The importance of exercise in treating diabetes

This page is critiquing the article 'Make your diabetic patients walk: long-term impact of different amounts of physical activity of type 2 diabetes' conducted by Loreto C and her associates, published in the Diabetes Care Journal in 2005.



What is the background to this research?
Diabetes Mellitus is becoming increasingly prevalent with the number of people suffering from this disease rising from 108 million in 1980 to 422 million in 2014. This chronic disease occurs when either the pancreas does not produce sufficient levels of insulin or when the body cannot use the insulin effectively. Diabetic patients have an increased risk of major complications, such as; blindness, kidney failure and cardiovascular diseases. As the number of people around the world being diagnosed with Type 2 Diabetes continues to grow, the availability and research into treatments and preventions for this disease is a major focus in the medical community. Using exercise as a management tool has been well recognised in the research community and is one of the first treatments they recommend their patients to implement. In the article; Make your diabetic patients walk: long-term impact of different amounts of physical activity of type 2 diabetes', they determine what are the physiological and biochemical benefits of different increments of aerobic exercise on Type 2 Diabetes.

Where is the research from?
The research was undertaken at the University of Perugia, in Italy. The two year study began in October 1999 and ceased in December 2002. Chiara Loreto, the lead researcher, is a diabetic specialist that focuses on out-patient care. She has completed 9 publications, with 8 of these concentrating on Diabetes Mellitus and Insulin Resistance. She has 859 citations, with 36 of these being in highly influential articles.

What kind of research was this?
This study was a randomised controlled trial (RCT), examining the 2-year impact of an exercise counselling intervention and different increments in energy expenditure on several physiological and biochemical outcomes. RCTs are most commonly used to estimate the effectiveness of a new intervention/treatment on a particular population, such as the intervention on physical activity on Type 2 Diabetic patients. This type of study minimises the risk of bias, providing an accurate tool to effectively examine the cause-effect relationships between an intervention and the outcome. RCTs are original research studies that contain unfiltered information, without appraisal and analysis by fellow researchers, the results are more difficult to apply into practice.

What did the research involve?
The research was conducted on 179 participants that fit into the following criteria:

Eligibility Criteria

 * Diagnosis of Type 2 Diabetes of at-least 2 years
 * Over the age of 40 years

Exclusion Criteria

 * Suffering from an illness that could reduce life expectancy or cause cardiac, liver or renal failure

Summary of the Research Design and Methods

 * 1) Once these participants had been deemed eligible, they were admitted into an unspecified outpatient diabetes clinic from October of 1999 to the following January of 2000.
 * 2) Each participant was provided with a 30 minute counselling session with a physician. This session provided participants with general guidelines in regard to exercise intensity, frequency and duration that was safe for them to participate in. Majority of participants were cleared to complete aerobic activity that was 40-60% of their Heart Rate Reserve.
 * 3) All participants were provided with a structured meal plan, consisting of 55% complex carbohydrates, 30% fat and 15% protein. Furthermore, all overweight and obese participants were placed on a daily 300kcal deficit meal plan.
 * 4) The participants voluntary physical activity was evaluated every three months via a Modifiable Activity Questionnaire (MAQ), they recorded the duration (hours per week) of various physical activities. However, they were instructed to record the type, intensity and duration performed of all physical activity daily in order to minimise recall bias.
 * 5) From the data collected via the MAQ, the researchers were able to estimate the amount of metabolic equivalent (METS) that each participant was completing each week. They then split the participants into 6 groups: 0 METs, 1-10 METs, 11-20 METs, 21-30 METs, 31-40 METs, >40 METS.

Strengths

 * By allowing the participants to complete voluntary exercise, rather than assigning certain METs to each individual, conveys that the exercise is maintainable to fellow diabetic patients.


 * The selection criteria and sample size allowed for a greater range of participants, allowing for the results to be more applicable for the greater diabetic population.


 * The researchers acknowledged their limitations and did not overemphasise the significance of their results.

Limitations

 * Exercise intensity and duration was self-reported by the participants through a MAQ. This is important to consider as self-reported questionnaires can cause bias, where participants may overestimate their exercise, causing limited validity and reliability . This could be rectified by supplying each participant with an accelerometer, providing more accurate physical activity data.


 * Placing the participants on structured meal plans tailored to their disease may have contributed to the results. Therefore, it is understandable to question whether these results were due to physical activity or the combination of physical activity and the meal plan.

What were the basic results?

 * In Table 1, we can see gradual improvements through increased increments of physical activity, with considerate to Group >40 METs, where we begin to see a decline in the benefits.


 * We see the most benefits in Group 31-40, who completed around 36-38.6METs/h/week, with greater improvements in weight, HbA1C and 10 year CHD risk.

What conclusions can we take from this research?
From the results provided from this study, we can conclude that participating in physical activity does have benefits on the health of Type 2 Diabetic patients. Several scientific societies recommend completing 30 minutes of moderate intensity exercise daily, equating to >20 METs/h/week, which from the results of this study does show benefits. However, the results from this study would suggest that in order to encompass the full health benefits that exercise can provide, a target of 27 METs/h/week is suggested, which corresponds to a 5km walk (1 hr) each day.

Although, multiple studies show that the incorporation of both aerobic and resistance training reap more benefits than solely completing aerobic exercise. With improvements in glycemic control, insulin resistance, fat mass, blood pressure, strength and lean body mass being observed in Type 2 Diabetics engaging in resistance training.

Practical advice
Recommendations of lifestyle measures that should be included in the management of Type 2 Diabetics include;


 * Complete at least 30 minutes of moderate intensity exercise each day, however aim for one hour


 * Complete a combination of aerobic and resistance training


 * Remember than any exercise is better than no exercise

Further information/resources
For further information regarding Diabetes Mellitus:

Diabetes Australia

World Health Organisation - Type 2 Diabetes

Nutritious Recipes for Diabetic Patients

National Diabetes Services Scheme