Exercise as it relates to Disease/Physical activity interventions to reduce cardiovascular risk factors in adolescents with type 1 diabetes

This article is a discussion of the article "Is exercise a therapeutic tool for improvement of cardiovascular risk factors in adolescents with type 1 diabetes mellitus? A randomised controlled trial." published by Salem et al. in 2010.

What is the background to this research?
Development of atheroscleroses (fatty plaque build-up on bloody vessel walls) has been shown to begin in childhood, and individuals with Type 1 diabetes mellitus (T1DM) have been shown to have an even higher risk of developing atherosclerotic conditions. Prior research has also demonstrated that high levels of blood low-density lipoproteins (LDL-c), triglycerides (TG), glycosylated haemoglobin (HbA1c); low levels of blood high-density lipoproteins (HDL-c); and high body mass index (BMI); have been associated with developing atherosclerotic conditions. Physical activity has been show to produce favourable changes to atherosclerosis risk factors in non-T1DM individuals. However, the changes to atherosclerotic risk facts in T1DM individuals in response to physical activity is less well understood. Post exercise, blood glucose levels in T1DM individuals typically fall if adequate carbohydrate is not consumed, or excess insulin is administered. Low blood glucose may result in a severe hypoglycaemic event, which may result in seizure, coma, or death. Somewhat understandably, many T1DM individuals report maintaining elevated blood glucose levels post exercise for fear of suffering a hypoglycaemic event. These elevated blood glucose levels may ultimately reflect higher HbA1c scores. The study by Salem et al in 2009 sought to further investigate changes to atherosclerotic risk factors, as well as incidence of severe hypoglycaemic events, in juvenile T1DM patients after a six month physical activity intervention.

Where is the research from?
The study took place at the Diabetes Specialized Clinic Children's Hospital, at Ain Shams University (Cairo, Egypt) between February 2009 and November 2009.

What kind of research was this?
Salem's study was a randomised control trial consisting of two different frequencies of physical activity intervention. One trial group performed the intervention once per week, the second trial group performed the intervention three times per week, and the control trial group did not perform the intervention. The National Health and Medical Research Council of Australia considers randomised control trials as the "gold standard" for conducting clinical trials, suggesting the study provides strong evidence to the relationship between physical activity and reducing cardiovascular risk factors in adolescents with T1DM.

What did the research involve?
The study involved 196 (75 male, 121 female) individuals, with an average age of 14.78 (±2.31) years. Participants had been diagnosed with T1DM at least three years prior to the study, and had a HbA1c of ≥7.5% for six months preceding the study. Participants were divided in one of three groups: control, exercise once per week, and exercise three times per week. Participants in the exercise groups performed a physical activity program involving aerobic, anaerobic, flexibility, and proprioceptive components for six months. Exercise parameters were adjusted as participants became conditioned to their training. Control group participants were required to abstain from formal exercise programs, nor were they able to alter their physical activity levels for the six month period. The researchers involved assessed: Body Weight, Body Mass Index, Waist Circumference, Blood Pressure (systolic and diastolic), Insulin Dosage, Hypoglycaemic Attacks, HbA1c Level, and Blood Lipid Profile (HDL, LDL, and TAG) before commencing the study, and at the end of the study.

What were the basic results?
The basic results from Salem's study showed that exercise was associated with:
 * Positive changes in Body Mass Index (↓)
 * Positive changes in HbA1c (↓)
 * Positive changes in Blood Lipid Profiles (↓LDL-c, ↓TG, ↑HLD-c)

The group which participated in physical activity three times per week showed greater improvements that the group which only participated once. The control group showed negative increases in some atherosclerotic risk factors.

Incidence of severe hypoglycaemic events was not significantly different between the three intervention groups.

How did the researchers interpret the results?
Salem et al concluded that exercise may positively influence individuals with T1DM in terms of cardiovascular risk factors, without negatively increasing their risk of severe hypoglycaemic events.

What conclusions should be taken away from this research?
The study has shown it is possible to positively alter cardiovascular risk factors in adolescents with T1DM via participation in regular physical activity.

However, similar studies, as cited by Salem, have produced conflicting results. Studies with differing age brackets, exercise regimes, and/or exercise focuses (eg. Aerobic vs Anaerobic) have been shown to improve only one of the many atherosclerosis risk factors assessed by Salem, or show no significant change. Perhaps the reason that the Salem study was more successful than other trials was their multi-faceted approach (Aerobic, Anaerobic, Flexibility, Proprioception) to exercise, which included components that became progressively more difficult as conditioning took place. This suggests the need for more studies relating to responses to physical activity in individuals with T1DM, across age groups and exercise modalities.

Additionally, Salem highlighted the need to develop methods to encourage those with T1DM to regularly participate in physical activity. This is especially crucial to those who avoid exercise due to fear of severe hypoglycaemic events. While some studies have investigated nutrition and counseling, Salem did not discuss the possibility of prescribing nutrition programs and/or T1DM management counselling for the six-month period, nor its potential impact on atherosclerotic measures or hypoglycaemic events.

What are the implications of this research?
The study by Salem has demonstrated a physical activity intervention which is capable of reducing atherosclerotic risk factors in juveniles with T1DM. This is of great importance, as evidence suggests that controlling risk factors at a young age results in reduced T1DM-complications and co-morbidities at later age groups. While further aspects of T1DM physical activity responses, nutrition programs, and management counselling need to be investigated, the study provides a step forward in promoting life-long health outcomes for those with the condition.