Exercise as it relates to Disease/Metabolic Effects of Aerobic Training and Resistance Training in Type 2 diabetes

This is a summary and analysis of the journal article "Metabolic Effects of Aerobic Training and Resistance Training in Type 2 Diabetic Subjects" by Bacchi et al. (2012).

What is the background to this research?
What is Type 2 Diabetes?

Type 2 Diabetes Mellitus (T2DM) is a condition that occurs when the body is unable to use insulin effectively and/or there are insufficient levels of insulin, which affects the body’s ability to regulate blood glucose levels. Type 2 Diabetes is often associated with a genetic predisposition, however there are a number of lifestyle factors that put individuals at a much higher risk of developing the condition. These include:
 * High blood pressure
 * Being overweight
 * Physical inactivity
 * Poor diet
 * Excess fat around abdominal area



Symptoms

Some individuals may never experience symptoms, however common symptoms can include the following:
 * Excessive thirst
 * Excessvie hunger
 * Frequent urination
 * Fatigue
 * Blurred vision
 * Headaches
 * Delayed healing
 * Leg cramps

Diagnosis

The standard process of diagnosing Type 2 Diabetes involves 3 stages:
 * 1) AUSDRISK - risk assessment
 * 2) Fasting plasma glucose test
 * 3) Oral Glucose Tolerance Test (OGTT)

Treatment

Type 2 Diabetes is typically treated initially by modifying appropriate lifestyle factors, such as a healthy diet and increased physical activity, as well as regularly monitoring blood glucose levels. Depending on the severity and progression of the condition however, medication and insulin may also be used in treatment.

The prevalence of diabetes is rapidly growing, with numbers rising from 108 million people worldwide to 422 million, in just 34 years. Currently, over 90% of these individuals have Type 2 Diabetes, which demonstrates the significance of research in this area, particularly regarding effective interventions.

Where is the research from?
This research was conducted in the diabetic outpatient clinic in the City Hospital in Verona, Italy. There were 13 authors involved in the article, all of which were from the University of Verona, from the following departments:
 * Medicine
 * Endocrinology and metabolic diseases
 * Public health and community medicine
 * Radiology
 * Neurological, neuropsychological and morphological movements sciences

What kind of research was this?
This study was a randomised controlled trial, which is considered by the NHMRC evidence Hierarchy as level II evidence. The only higher level of evidence (Level I) is systematic reviews of level II studies.

What did the research involve?
Subjects and randomisation

The study selected 40 patients from the Diabetic Outpatient Clinic between September 2008 and February 2010, with follow-up until June 2010. Inclusion criteria for the study were:
 * Type 2 Diabetes for at least 1 year
 * Age 40- 70
 * HbA1c 6.5 - 9.0%
 * BMI 24 -36
 * Baseline physical activity <1000 METs min per week (IPAQ Questionnaire)
 * No diabetes medications except oral hypoglycemics

The study also had clear exclusion criteria, which helps to ensure participants are similar at baseline and also minimises the risk of adverse events. Participants were allocated to either the aerobic training or resistance training group, and allocation was carried out by an external individual who was blinded to names and details of patients.

Intervention

Both groups participated in their specific exercise three times per week for four months at the fitness centre of the Exercise and Sport Science School of Verona University. The aerobic training involved using cardiovascular equipment at 60-65% of HRR and the resistance training involved both machine and free weights, for all major muscle groups, at 10 reps of 30-50% 1 repetition max (1RM). This was gradually increased to 70-80% 1RM.

Outcomes

Primary:
 * HbA1c levels^

Secondary:
 * Insulin sensitivity
 * Beta cell function
 * Cardiorespiratory fitness
 * Muscle strength
 * Body composition
 * Metabolic profile

^ HbA1c is ‘glycated haemoglobin’ which is a protein that joins with glucose (blood sugar) in the blood. Measuring HbA1c therefore gives an average plasma glucose concentration.

What were the basic results?
38 of the original subjects completed the intervention, and results showed that both aerobic and resistance training is effective at lowering HbA1c, with aerobic exercise lowering by 0.40% and resistance training lowering by 0.30%. Results also found both groups showed similar improvements in insulin sensitivity and reduced abdominal visceral fat.

What conclusions can we take from this research?
In summary, the results of this study have shown that aerobic training and resistance training are equally effective at reducing HbA1c in Type 2 Diabetics, and both also provide further health improvements. These reductions in HbA1c however, are quite small, which is important to consider when interpreting these results.

This study demonstrated a number of strengths including:
 * Randomisation of subjects
 * Clear inclusion/exclusion criteria
 * Blind assessors
 * Appropriate and specific outcome measures
 * Follow-up of participants

The weaknesses of the study included:
 * Minimal introduction to the topic and other research in the field
 * Small sample size (N=40)
 * No control/non-intervention group

Overall, the study was of moderate quality, and the results can be considered reliable. Further research in this field could be improved by addressing the above limitations.

Practical advice
Exercise as a way of managing Type 2 Diabetes has been previously well researched and shown to be highly effective, however much of this research has focussed on aerobic exercise. It is now clear that resistance training provides very similar benefits, and should therefore be considered when designing an exercise program for Type 2 Diabetics. Resistance training is also important for a number of other health benefits, and prescription for diabetics is very similar to healthy individuals, with a recommended frequency of 2-3 times per week. Type 2 Diabetics should seek the assistance from an accredited exercise physiologist or other appropriate health professional for specific exercise prescription.

Further information/resources
For further information and helpful resources, please see the links below:

https://www.diabetesaustralia.com.au
 * Diabetes Australia

https://www.diabetes-act.com.au
 * Diabetes ACT

http://www.health.gov.au/internet/main/publishing.nsf/content/health-pubhlth-strateg-phys-act-guidelines
 * Physical Activity Guidelines