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Title: The assessment and management of glycaemic control and vascular risk in people with type 1 diabetes
Author: Wallymahmed, Maureen Elizabeth
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2012
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Introduction: Type 1 diabetes is a common cause of chronic disease in young people. Over the past few decades a worldwide rise in incidence has been observed, particularly in children under the age of 5 years. life expectancy is reduced with the major causes of mortality being renal and cardiovascular disease. Good glycaeamic control has been shown to reduce the risk and progression of micro and macro vascular complications in type 1 diabetes. However, in many people, target HbA1c levels are difficult to achieve without increasing the risk of hypoglycaemia. In the past, there has been a tendency to focus on the prevention of microvascular complications, especially in young people with type 1 diabetes. However it is clear that type 1 diabetes is associated with an increased risk of cardiovascular disease and therefore a shift in emphasis towards global risk factor reduction may be indicated. This could include the management of glycaemia and cardiovascular risk factors involving lifestyle and pharmacological interventions. Aims: This thesis consists of four related studies of aspects of glycaemic and cardiovascular risk factor management in people with type 1 diabetes. The aims of these studies were: (1) Audit: To assess the achievement of glycaemic control and cardiovascular risk factor targets in people with type 1 diabetes attending a routine hospital based diabetes clinic. (2) Physical activity and glycaemic control: To clarify the relationship between aerobic fitness and glycaemic control in people with type 1 diabetes and identify the management strategies adopted by people with type 1 diabetes to maintain blood glucose control and avoid hypoglycaemia during physical activity. (3) Nurse led intervention versus routine care: To compare the effects of a nurse-led risk factor reduction clinic with routine diabetes care in achieving glycaemic and cardiovascular risk factor targets (4) Glycaemic "streaming": To investigate the stability of long term glycaemic control in a group of people with type 1 diabetes over a 5 year period, examining the possible phenomenon of glycaemic "streaming". Methods: The basic investigative methods for the 4 studies were: (1) Audit: A case note review of 218 people with type 1 diabetes. Demographic and risk factor target information (weight, HbA1Cl blood pressure, lipid profile and albumin: creatinine ratio) were collected. The same group was reassessed 3.5 years later. (2) Physical activity and glycaemic control:To assess the relationship between physical activity and glycaemic control aerobic capacity was assessed using the Chester Step Test in 141 people with type 1 diabetes. In addition self reported physical activity, frequency of hypoglycaemia and hypoglycaemic avoidance behaviour was assessed using a simple 'in-house' questionnaire in 50 of the 141 people who had completed the Chester Step Test. (3) Nurse led intervention versus routine care:To compare the effects of nurse-led intervention with routine care, 81 people with type 1 diabetes with an HbA1c ≥8.0% and at least one other risk factor for the development of cardiovascular disease were randomised to receive either routine care or nurse-led intervention. HbA1c, non-fasting lipid profile, blood pressure, weight, BMI and insulin dose were recorded at baseline, 6, 12 and 24 months. (4) Glycaemic "streaming": To examine long term glyceamic control a retrospective analysis of glycaemic control in a cohort of 181 people with type 1 diabetes (2003-2007) was conducted. Basic demographic data, sequential HbA1c" first and last HbA1c, and mean HbA1c,for the 5 year period was collected. Results: The results of each of the 4 studies are as follows: (1) Audit: Mean HbA1c was 9.7±1.9%, mean total cholesterol was 5.1±1.1 mmol/I, mean systolic blood pressure was 113±18 mmHg and mean diastolic blood pressure was 64±10 mmHg. Target HbA1c, (::; 7.5%) was achieved in only 7.9% of those audited, 54.6% had a total cholesterol above target (>4.8 mrnol/l), 13.1% had a systolic blood pressure above target (>135mmHg) and 3.8% had a diastolic blood pressure above target (>85mmHg). At re-audit mean HbA1c and total cholesterol had improved significantly and mean systolic and diastolic blood pressure had increased significantly. (2) Physical activity and glycaemic control: Initial data revealed a positive correlation between aerobic capacity and HbA1c (r=0.17, p<0.05), indicating that those with good aerobic capacity have poorer glycaemic control. Further investigation, involving 50 people with type 1 diabetes, revealed that 78% of this group took some action to prevent hypoglycaemia during physical activity despite there being no previous experience of serious hypoglycaemia associated with physical activity. (3) Nurse led intervention versus routine care: Compared with routine care, nurse-led intervention led to significant improvements in HbA1c (10.1±1.4 v 9.3±1.4%, p<0.001 total cholesterol (5.8±0.9 v 4.3±1.0 mrnol/l, p<0.001 systolic (127±22 v 115±13 mmHg, p<0.001) and diastolic blood pressure (71±13 v 65±9 mmHg, p<0.05) at 12 months. At 24 months improvements were maintained in all variables except diastolic blood pressure. In the control group only total cholesterol improved significantly after 12 months (5.9±0.9 v 5.2±1.0 mmHg, p<0.001) and this was maintained at 24 months. (4) Glycaemic "streaming":Over the 5 year study period there was a small but significant improvement in mean HbA1c in the cohort studied (181 patients) (9.0 ± 1.6 to 8.7 ± 1.5%, P = 0.003). This was accounted for by improvements in males (8.9 ± 1.6 to 8.6 ± 1.4%, P = 0.005) and those with poor control (HbA1c > 8.0%) (9.4 ± 1.4 to 9.0 ± 1.4%, P = 0.002). Females and well controlled patients did not show any improvement in mean glycaemic control. Conclusions: The basic audit data indicated that the majority of people with type 1 diabetes involved in the study had an HbA1c and lipid profile outside of the target range regardless of being managed in a clinic staffed by a multidisciplinary diabetes team experienced in the management of type 1 diabetes. Although over a 3.5 year follow- up period mean HbA1c and total cholesterol improved significantly. The majority of patients still had an HbA1c and total cholesterol above target levels. Life advice such as the encouragement of physical activity is a routine part of diabetes care on the assumption that this will have beneficial effects on glycaemic control and cardiovascular risk factors. However, the study of physical activity and glycaemic control included in this thesis, has demonstrated that increased aerobic capacity, indicating greater physical fitness, was associated with poorer glycaemic control. Further investigation revealed that this may be due to action taken by people with type 1 diabetes to avoid potential hypoglycaemia (increasing carbohydrate consumption, reducing insulin or a combination of both) which may have had a detrimental effect on glycaemic control. These findings indicate that people with type 1 diabetes require more education on the management of blood glucose during physical activity. Routine diabetes follow up reviews can be complex and time consuming with a focus not only on presenting problems but also on routine screening, risk factor reduction and lifestyle issues. The achievement and maintenance of target HbA1c levels on a long term basis can be difficult for many people with type 1 diabetes. There are several possible reasons for this. Even with modern insulin regimens it is difficult to mimic physiological insulin secretion. In addition it is possible that for some patients the drudge of the day to day self management of type 1 diabetes leads to fatigue of the efforts required. It is also plausible that concern about hypoglycaemia, leading to intentional raised blood glucose levels, may contribute to poor glycaemic control. Furthermore there may be a tendency to a "streaming" effect. In the glycaemic "streaming" study included in this thesis, a small overall improvement in HbA1c was noted over a 5 year time period. However, most patients maintained similar glycaemic control over the study period adding strength to the small body of data on the phenomenon of glycaemic "streaming". Alternatively poor glycaemic control may reflect the system of health care delivery. It may be that to achieve optimal diabetes care particular problems need to be identified and managed in a specific clinic staffed by experienced health care professionals. Traditionally diabetes specialist nurses have focused mainly on glycaemic control. However many of the lifestyle issues which impact on glycaemic control also influence blood pressure and lipid profile. In the randomised controlled study reported in this thesis nurse led intervention resulted in beneficial effects on glycaemic and cardiovascular risk targets in type 1 diabetes most of which were maintained at 24 months. These improvements may be a feature of being seen more frequently by the same person. Nurse led intervention, particularly in the first 6 months, involved identification of individual goals and regular review of these goals which may have increased motivation. Also a change in focus to global risk factor reduction, rather than just glycaemic control may have had a beneficial effect. In addition improvements in risk factors were associated with a greater use of anti-hypertensive and lipid lowering agents. The findings reported in this thesis have significant implications for practice. Targeted nurse-led global risk factor reduction may be a more effective system of achieving risk factor targets in patients with type 1 diabetes, freeing medical staff to deal with more complex cases. Adopting a global approach may encourage patients to make lifestyle changes to reduce cardiovascular risk which also have beneficial effects on glycaemic control.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available