The effects of a combined aerobic and resistance exercise programme on physiological parameters and metabolic control in type 1 and 2 diabetes
Diabetes is a common chronic disease that affects almost all countries in the world and has continued to increase at an alarming rate in the last decades. It kills a person every seven seconds. Recent thinking treats both types of diabetes as inflammatory diseases. The aim of the thesis was to obtain a better understanding of the relationship between exercise and the management of diabetes by conducting surveys and experimental work. It investigates the effects of exercise on the physiology and metabolic control in Type 1 (T1D) and Type 2 diabetes (T2D), using non-diabetic (ND) people as a control. The management and treatment of T1D and T2D volunteers were first assessed in surveys and the novelty was second to expose both to exercise. In the latter, volunteers were compared biochemically including for inflammatory responses to their illness and to practical exercise. Four studies were undertaken in this thesis involving a mixed approach: questionnaire based studies (first and second surveys) and experimental based studies (first and second exercise studies). The first survey study was about insulin users with opinions gathered from both T1D and T2D (T2I) respondents (n=707). In this survey diabetic people were asked about the condition and coping strategies for the difficulties using insulin in daily life. The first survey does touch on exercise but only as part of the larger picture. The second survey study (n=240) evolved from the first one and was again about opinions but in this case oral anti-hyperglycaemics were included in the management of T2D respondents (T2T). This survey focused more strongly on the role of exercise. The surveys were conducted by post, email and online while detailed statistical analysis followed. Two exercise studies with the same volunteers (n=25; ND=7, T1D=7, T2T=7, T2I=4) were then carried out based on some findings of the surveys. These studies explored the effects of a combination of aerobic (AE) and resistance exercise (RE) components for a six week period on diabetes. The methodology of the first exercise study concentrated on the physiological variables, involving the use of exercise and measurement equipment to monitor for expired gases and anthropometric changes. Substrate oxidation, blood profiles for lipid, blood glucose (BG) and glycated haemoglobin (HbA1c) were also assessed. The second exercise study builds on this with specific inflammatory marker profiles such as tumour necrosis alpha (TNF-α), interleukin-6 (IL-6), leptin and resistin on ND, T1D and T2D volunteers over the same time period as in the first exercise study. The first survey study showed that many respondents (13-47%) lacked adequate professional information about the various separate aspects of their insulin-treated illness. For example, 38% of T1D and 28% of T2I reported that they did not have enough information regarding raised cholesterol levels. The results for diabetes complications revealed that T2I had greater complications compared to T1D (for example angina 18.5% for T2I compared to 4.6% for T1D), although the groups could not be matched for age, reasons for responding to the survey, duration of illness or severity of illness when starting insulin. The second survey revealed that insulin users often had an HbA1c that did not meet best practice expectations of 6.5% - 7.5% (48 -58 mmol/mol). It also showed that those who did exercise regularly were more likely to have acceptable HbA1c values (5-7% or 31-53mmol/mol), than those who did not. This is especially the case for the type 2 groups (eg for T2T 46% exercising compared to 31% non-exercising) who were less likely (19% respondents compared to 25%) to have HbA1c over 8% or 64 mmol/mol. It was of interest to know the risks, barriers and likely recommendations for the two groups. For example, fewer T2I people test BG frequently (12.5% compared to T1D 62%, testing four or more times daily), even when they are insulin basal bolus users, which could foster hypoglycaemic events during exercise. The findings of the first and second surveys showed that managing diabetes in the 21st century remains difficult for many people, despite the availability of diagnostic, monitoring and medication improvements. This leads to anxiety and illness over the short and long term. In the first exercise study, it was clear that for this combined exercise regimen, the chronic effects were notable. The most significant finding was that the effect of 6 weeks was the drop in HbA1c in all groups ND from 5.4-5.2% or 36-33mmol/mol (p ˂ 0.01), T1D 7.0 to 6.7% or 53-50mmol/mol (p ˂ 0.01), T2T 7.6 to 7.2% or 60-55mmol/mol (p ˂ 0.05), T2I 7.3 to 6.8 or 56-51mmol/mol (p ˂ 0.05). This is equivalent to raising insulin or other medication and while clearly very beneficial, especially as occurring as a result of moderate exercise over only 6 weeks. Lipid factors showed improvements, not all significantly but these were likely to be influenced by support medication such as statins. However, the heart rate (HR) and blood pressure (BP) reduced at rest for all groups over the six weeks. The respiratory exchange ratio (RER), a measure of substrates oxidation showed that the carbohydrate metabolism was steady. The muscular strength and the subjective assessment improved after the exercise period. The second exercise study showed the interleukin 6 levels fell with the chronic effects of combined exercise ND (3.97-2.7pg/ml), T1D (2.15-1.02 pg/ml), T2T (3.67-2.72pg/ml) and T2I (3.66-1.17pg/ml) as did TNFα and other cytokine levels which may thus be cardioprotective. This suggests that exercise could be part of the anti-inflammatory treatment of T1D and T2D. To conclude, the findings of the two survey studies showed that the management of diabetes is difficult for many diabetics. Furthermore, the exercise studies demonstrated that a regular combined (RE and AE) exercise trial at moderate intensity for six week could be physiologically beneficial for diabetics. The underlying mechanism for this could be improvements in glycaemic control, lipid profile, cardiovascular fitness level and strength, as well as the inflammatory features of both T1D and T2D.
- PhD