Prediction of 10-year vascular risk in patients with diabetes: the AD-ON risk score.

AIMS: To formulate a combined cardiovascular risk score in diabetes that could be useful both to physicians and healthcare funders. METHODS: Data were derived from the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation Observational (ADVANCE-ON) study, a randomized controlled trial (mean duration 5 years) with a post-randomization follow-up (mean 4.9 years), that included 11 140 high-risk patients with diabetes. The outcome analysed was the occurrence of either fatal or non-fatal macrovascular or renal disease. A Cox regression model was used to determine weightings in the risk score. The resultant score was recalibrated to each of three major global regions, as covered by the ADVANCE-ON study. RESULTS: Over a median of 9.9 years, 1145 patients experienced at least one component of the combined outcome event. The resultant score, the AD-ON risk score, incorporated 13 demographic or clinical variables. Its discrimination was modest [c-statistic = 0.668 (95% confidence interval 0.651, 0.685)] but its calibration was excellent (predicted and observed risks coincided well, within disparate global regions). In terms of the integrated discrimination improvement index, its performance was marginally superior, over a 10-year risk horizon, to existing risk scores in clinical use, from a restricted version of the same data, for macrovascular and renal disease separately. CONCLUSIONS: The AD-ON risk score has advantages over the existing vascular risk scores in diabetes that used data from the original ADVANCE trial, which treat macrovascular and renal diseases separately. These advantages include its simplicity of use and global application.

An assessment of lifestyle video education for people newly diagnosed with type 2 diabetes.

BACKGROUND: Education plays a key role in the development of self-management skills for people with type 2 diabetes, although there is limited evidence for the use of video education. AIMS: To develop a video-based lifestyle education programme for people newly diagnosed with type 2 diabetes and to evaluate changes in knowledge, biomedical indices and quality of life. METHODS: Forty-two newly diagnosed type 2 diabetic subjects were recruited and randomly allocated to either a video education or control group. Data were collected at baseline and 6 months after the intervention. Subjects (43% male) had a mean (SD) age of 60.8 (9.6) years, weight 89.5 (15.5) kg, BMI 31.3 (5.1) kg m(2), glycated haemoglobin (A1c) 7.4 (1.7)%, total cholesterol 4.7 (1.2) mmol L(-1), high-density lipoprotein cholesterol 1.15 (0.34) mmol L(-1), triglycerides 1.8 (1.0) mmol L(-1), low-density lipoprotein cholesterol 2.8 (1.0) mmol L(-1), pedometer reading 5721 (3446) steps per day. There were 63.7% correct answers given to the ADKnowl questionnaire and the WHO-5 Well-Being score was 65.8%. RESULTS: At 6 months, the intervention group showed increased knowledge compared to controls (74.3% versus 56.4% correct answers, P < or = 0.0001). Although there were no significant differences in changes over 6 months between the two groups, the intervention group showed improvements in A1c (-0.7%, P = 0.024), total cholesterol (-0.5 mmol L(-1), P = 0.017), low-density lipoprotein cholesterol (-0.5, P = 0.018) and increased physical activity measured by pedometer (1266 steps per day, P = 0.043) from baseline, with no significant changes in the control group. CONCLUSIONS: A brief video intervention increased diabetes knowledge amongst those newly diagnosed with type 2 diabetes and may comprise an effective way of directing education to such individuals.

Glycaemic risk assessment in children and young people with Type 1 diabetes mellitus.

AIM: To ascertain if those with diabetes (and their carers) ascribe a similar level of risk to blood glucose control as healthcare professionals. METHODS: We used a structured questionnaire to ask fifty healthcare professionals how 'dangerous' a given blood glucose value was. Their answers were modelled to produce an algorithm of assessed risk. To examine if patients (and their carers) would apportion a similar level of risk to that of healthcare professionals, the same questionnaire was issued to fifty children and adolescents with Type 1 diabetes. For patients under 8 years old the carers completed the questionnaires (n = 23). Both patient and carers together completed the questionnaire for those aged 8-11 years (n = 15) and patients over the age of 11 years completed the questionnaire themselves (n = 12). The median results and interquartile range of the assessed level of risk, as determined by the two groups, were compared using a generalized linear model. RESULTS: A significant difference (P < 0.0001) was identified between the median risk assessments of the two groups. The zero level of assessed risk was upward shifted in the patient group by 0.8 mmol/l and indicated the patients' view of risk increased. CONCLUSIONS: Patients with Type 1 diabetes (and their carers) evaluate the risk from blood glucose values differently from healthcare professionals. The euglycaemic state (zero ascribed risk) that patients chose was 0.8 mmol/l greater than that of healthcare professionals, indicating, perhaps, hypoglycaemia avoidance, a more pragmatic approach or less exposure to current trends in glycaemic control.

Patient and provider perceptions of care for diabetes: results of the cross-national DAWN Study.

AIMS/HYPOTHESIS: We assessed country-level and individual-level patterns in patient and provider perceptions of diabetes care. METHODS: The study used a cross-sectional design with face-to-face or telephone interviews of diabetic patients and healthcare providers in 13 countries from Asia, Australia, Europe and North America. Participants were randomly selected adults with type 1 or type 2 diabetes (n=5,104), and randomly selected diabetes-care providers, including primary-care physicians (n=2,070), diabetes specialist physicians (n=635) and nurses (n=1,122). Multivariate analysis was used to examine the relationships between outcomes and both country and respondent characteristics, and the interaction between these two factors. RESULTS: Providers rated chronic-care systems and remuneration for chronic care as mediocre. Patients reported that ease of access to care was high, but not without financial barriers. Patients reported moderate levels of collaboration among providers, and providers indicated that several specialist disciplines were not readily available to them. Patients reported high levels of collaboration with providers in their own care. Provider endorsement of primary prevention strategies for type 2 diabetes was high. Patients with fewer socio-economic resources and more diabetes complications had lower access (and/or higher barriers) to care and lower quality of patient-provider collaboration. Countries differed significantly for all outcomes, and the relationships between respondent characteristics and outcomes varied by country. CONCLUSIONS/INTERPRETATION: There is much need for improvement in applying the chronic-care model to the treatment and prevention of diabetes in all of the countries studied. Each country must develop its own priorities for improving diabetes care and comparison with other countries can help identify strengths as well as weaknesses.

Cost-utility analyses of intensive blood glucose and tight blood pressure control in type 2 diabetes (UKPDS 72).

AIMS/HYPOTHESIS: This study estimated the economic efficiency (1) of intensive blood glucose control and tight blood pressure control in patients with type 2 diabetes who also had hypertension, and (2) of metformin therapy in type 2 diabetic patients who were overweight. METHODS: We conducted cost-utility analysis based on patient-level data from a randomised clinical controlled trial involving 4,209 patients with newly diagnosed type 2 diabetes conducted in 23 hospital-based clinics in England, Scotland and Northern Ireland as part of the UK Prospective Diabetes Study (UKPDS). Three different policies were evaluated: intensive blood glucose control with sulphonylurea/insulin; intensive blood glucose control with metformin for overweight patients; and tight blood pressure control of hypertensive patients. Incremental cost : effectiveness ratios were calculated based on the net cost of healthcare resources associated with these policies and on effectiveness in terms of quality-adjusted life years gained, estimated over a lifetime from within-trial effects using the UKPDS Outcomes Model. RESULTS: The incremental cost per quality-adjusted life years gained (in year 2004 UK prices) for intensive blood glucose control was 6,028 UK pounds, and for blood pressure control was 369 UK pounds. Metformin therapy was cost-saving and increased quality-adjusted life expectancy. CONCLUSIONS/INTERPRETATION: Each of the three policies evaluated has a lower cost per quality-adjusted life year gained than that of many other accepted uses of healthcare resources. The results provide an economic rationale for ensuring that care of patients with type 2 diabetes corresponds at least to the levels of these interventions.

The assessment of insulin resistance in man.

BACKGROUND: Insulin resistance exists when a normal concentration of insulin produces a less than normal biological response. The ability to measure insulin resistance is important in order to understand the aetiopathology of Type 2 diabetes, to examine the epidemiology and to assess the effects of intervention. METHODS: We assess and compare methods of measurement and have undertaken a literature review from 1966 to 2001. RESULTS: Quantitative estimates of insulin resistance can be obtained using model assessments, clamps or insulin infusion sensitivity tests. There is considerable variation in the complexity and labour intensity of the various methods. The most well-established methods are the euglycaemic clamp, minimal model assessment and homeostatic model assessment (HOMA). No single test is appropriate under all circumstances. CONCLUSIONS: There are a number of well-established tests used to measure insulin resistance: the choice of method depends on the size and type of study to be undertaken. Although the so-called 'gold-standard' test, the euglycaemic clamp, is useful for intensive physiological studies on small numbers of subjects, a simpler tool such as HOMA is more appropriate for large epidemiological studies. It is important to be aware that most techniques measure stimulated insulin resistance whereas HOMA gives an estimate of basal insulin resistance. Caution should be exercised when making comparisons between studies due to variations in infusion protocols, sampling procedures and hormone assays used in different studies.

Fate of research studies.

A retrospective survey was conducted of 720 research protocols, approved by the Central Oxford Research Ethics Committee between 1984 and 1987, to determine the fate of research studies from inception. Forty-five per cent were clinical trials, 23% were observational studies and 32% were laboratory-based experimental studies. Further information was obtained on 487 studies, of which 287 (59%) had been completed, 100 (21%) had never started, 58 (12%) had been abandoned or were in abeyance and 42 (9%) were still ongoing, as of May 1990. Forty-three per cent of the original 487 studies were subsequently published or presented. The most frequent reason for not starting a study was failure to obtain funding (40%). The main reason for abandoning a study was difficulty in recruiting study participants (28%). Departure of one of the investigators from the institution and a variety of logistical problems were also common reasons for either not starting or abandoning a study. A thorough review of the pragmatic as well as the scientific aspects of a planned research project is important to minimize the initiation of studies that are unlikely to succeed.

The management of hyperlipidaemia: are specialist lipid clinics needed?

A survey of all general practitioners in Oxfordshire was undertaken to determine what use they wanted to make of a district lipid clinic, and to assess how effectively it met their needs. The response rate was 85% (288/340) but some respondents failed to answer each section of every question. One hundred and eighty-five general practitioners (64%) had previously referred patients to the clinic. Most respondents selectively asked for blood cholesterol measurements in patients with major cardiovascular risk factors (94%, 266/283), and few routinely asked for cholesterol as part of a health check (17%, 43/258). Most thought that referral to a clinic was appropriate for children (65%, 149/229), for patients aged 20 to 39 (85%, 209/247), and for older patients aged up to 60 (77%, 186/243). Ninety-four per cent (260/277) wanted access to specialist advice for patients with a cholesterol concentration exceeding 8.0 mmol l-1, and 73% (197/270) wanted specialist advice before starting treatment with a lipid-lowering drug. Although most respondents rated the service provided by the clinic favourably, more than half would have liked more information on prognosis, drug treatment, long-term follow-up, and screening of family members. We conclude that general practitioners would like access to specialist advice for the management of severe hyperlipidaemias, and that cardiovascular screening programmes in primary care have important resource implications for specialist services.

Simple empirical assessment of beta-cell function by a constant infusion of glucose test in normal and type 2 (non-insulin-dependent) diabetic subjects.

The plasma insulin or C-peptide response to a 90-min constant glucose infusion 5 mg.kg ideal body weight-1.min-1 provides Beta-cell assessment comparable to more intensive methods. In 14 diet-treated Type 2 (non-insulin-dependent) diabetic subjects and 12 non-diabetic subjects, plasma insulin and C-peptide concentrations gave near linear plots against simultaneous glucose values. The 'glucose-insulin and glucose-C-peptide vectors' (G-I and G-C vectors), could be extrapolated to predict insulin and C-peptide levels during a 12 mmol/l hyperglycaemic clamp. Predicted concentrations correlated with clamp concentrations, r = 0.94 and r = 0.98 respectively, p less than 0.001, validating the vectors as empirical glucose dose-response curves. The vector slopes correlated highly with %Beta, a mathematical model-derived measure of Beta-cell function using constant infusion of glucose model assessment, Spearman r = 0.95 and 0.93 for insulin and C-peptide, respectively. G-I vector slopes in 21 diet-treated Type 2 diabetic subjects with fasting glucose (mean + 1 SD) 7.5 +/- 2.3 mmol/l, were lower than in 28 non-diabetic subjects, (geometric mean, 1 SD range, 8.4 pmol/mmol (3.3-21.0) and 25.1 pmol/mmol (14.3-44.1), p less than 0.001, respectively), indicating an impaired Beta-cell response. The G-I vector slopes correlated with obesity in both groups (r = 0.54 p less than 0.02 and 0.72, p less than 0.001 respectively), and, in 15 non-diabetic subjects, correlated inversely with insulin sensitivity as measured by a euglycaemic clamp (r = -0.66, p less than 0.01). Thus, Beta-cell function needs to be interpreted in relation to obesity/insulin resistance and, taking obesity into account, only 4 of 21 diabetic patients had Beta-cell function (G-I vector slope) in the non-diabetic range. The fasting plasma glucose in the diabetic subjects correlated inversely with the obesity-corrected G-I and G-C vector slopes (partial r = -0.57, p less than 0.01 and -0.86, p less than 0.001, respectively). The insulin or C-peptide response to the glucose infusion provides a direct empirical measure of the Beta-cell function, which can be interpreted in relation to obesity or to insulin resistance to assess underlying pancreatic responsiveness.

Natural history of pancreatic islet B-cell function in type 2 diabetes mellitus studied over six years by homeostasis model assessment.

Islet B-cell function and insulin sensitivity were estimated with the aid of a mathematical model from repeated fasting plasma glucose and insulin measurements over a 6 year period in 131 patients with type 2 diabetes mellitus who could be managed satisfactorily on dietary therapy alone. They presented between the ages of 40 and 69 years, and were studied before and after one year of treatment, and then at regular intervals from 12 until 72 months later. A method of averaging the individual trends by means of a linear model regression technique was used to assess the progression of their diabetes. Dietary management over the first 12 months resulted in weight loss from 118% to 106% average body weight, and improved insulin sensitivity from 26% to 40% of normal (p less than 0.001). From 12 to 72 months, the fasting plasma glucose rose at a mean rate of 0.23 mmol/l per year (p less than 0.001) despite a rate of weight loss of 0.2% average body weight per year (p less than 0.01). The estimated islet B-cell function, expressed as a percentage of normal, decreased significantly (p less than 0.05) at a rate of 1.5% per year, with no statistically significant change in insulin sensitivity. Extrapolation suggests the reduction in B-cell function predated the departure of fasting plasma glucose from the normal range.

Continuous infusion of glucose with model assessment: measurement of insulin resistance and beta-cell function in man.

Continuous infusion of glucose with model assessment (CIGMA) is a new method of assessing glucose tolerance, insulin resistance and beta-cell function. It consists of a continuous glucose infusion 5 mg glucose/kg ideal body weight per min for 60 min, with measurement of plasma glucose and insulin concentrations. These are similar to postprandial levels, change slowly, and depend on the dynamic interaction between the insulin produced and its effect on glucose turnover. The concentrations can be interpreted using a mathematical model of glucose and insulin homeostasis to assess insulin resistance and beta-cell function. In 23 subjects (12 normal and 11 with Type 2 (non-insulin-dependent diabetes) the insulin resistance measured by CIGMA correlated with that measured independently by euglycaemic clamp (Rs = 0.87, p less than 0.0001). With normal insulin resistance defined as 1, the median resistance in normal subjects was 1.35 by CIGMA and 1.39 by clamp, and in diabetic patients 4.0 by CIGMA and 3.96 by clamp. In 21 subjects (10 normal and 11 Type 2 diabetic) the beta-cell function measured by CIGMA correlated with steady-state plasma insulin levels during hyperglycaemic clamp at 10 mmol/l (Rs = 0.64, p less than 0.002). The CIGMA coefficient of variability was 21% for resistance and 19% for beta-cell function. CIGMA is a simple, non-labour-intensive method for assessing insulin resistance and beta-cell function in normal and Type 2 diabetic subjects who do not have glycosuria during the test.

Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man.

The steady-state basal plasma glucose and insulin concentrations are determined by their interaction in a feedback loop. A computer-solved model has been used to predict the homeostatic concentrations which arise from varying degrees beta-cell deficiency and insulin resistance. Comparison of a patient's fasting values with the model's predictions allows a quantitative assessment of the contributions of insulin resistance and deficient beta-cell function to the fasting hyperglycaemia (homeostasis model assessment, HOMA). The accuracy and precision of the estimate have been determined by comparison with independent measures of insulin resistance and beta-cell function using hyperglycaemic and euglycaemic clamps and an intravenous glucose tolerance test. The estimate of insulin resistance obtained by homeostasis model assessment correlated with estimates obtained by use of the euglycaemic clamp (Rs = 0.88, p less than 0.0001), the fasting insulin concentration (Rs = 0.81, p less than 0.0001), and the hyperglycaemic clamp, (Rs = 0.69, p less than 0.01). There was no correlation with any aspect of insulin-receptor binding. The estimate of deficient beta-cell function obtained by homeostasis model assessment correlated with that derived using the hyperglycaemic clamp (Rs = 0.61, p less than 0.01) and with the estimate from the intravenous glucose tolerance test (Rs = 0.64, p less than 0.05). The low precision of the estimates from the model (coefficients of variation: 31% for insulin resistance and 32% for beta-cell deficit) limits its use, but the correlation of the model's estimates with patient data accords with the hypothesis that basal glucose and insulin interactions are largely determined by a simple feed back loop.