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Background:  Diabetes mellitus is a metabolic disorder of multifactorial aetiology which affects approximately 1.9 million adults in the UK. The incidence of type 2 diabetes is increasing with obesity levels, and treatment focuses on achieving and maintaining adequate blood glucose levels and weight management in order to reduce the risk of diabetic complications. As diabetes is progressive, blood glucose often becomes inadequate on maximal dose oral glucose lowering therapy and patients may eventually require insulin as third line therapy. Exenatide is an alternative to insulin; the first drug in the class of incretin mimetics which has been used at Darent Valley Hospital for the past 2 years. This study aimed to audit patient management against the 2009 NICE guidelines and to identify any health benefits following 6 months of Exenatide treatment.

Methods:  A convenience sample of 46 outpatients (n = 27 male; n = 19 female) in the Dartford and Gravesham area who were or had been taking Byetta, according to a list supplied by the Diabetes team, was utilised for this audit. Patients’ medical information was collected from the clinical record system ‘Diabeta’ and statistical analysis was carried out using SPSS (v17) to investigate changes in weight, body mass index (BMI) and HbA1C as a marker of drug efficacy (repeated measures ANOVA). Retrospective patient data was also utilised to assess compliance with the NICE guidelines for starting patients on Byetta and continuing treatment at 6 months.

Results:  At baseline the sample had a mean age of 57 (10.7) years and were predominantly obese [mean BMI 38.8 (8.4) kg m−2] with poor blood glucose control [mean HbA1c 10.0 (1.2)%]. Mean time since diagnosis was 9 (3.7) years. Overall, a significant reduction in weight was seen after 6 months of treatment (< 0.001) with a mean weight loss of 2.8 kg (0.6). BMI was significantly lower after 6 months (< 0.001) with a mean reduction of 1.5 kg m−2 (1.9). HbA1C was also significantly reduced after 6 months (< 0.001) with a mean reduction of 1.7% (1.5). Changes in weight, BMI and HbA1C were not significantly different between genders, time since diagnosis or age. The audit identified that the Diabetes team were following NICE guidelines for the majority of the time. When starting the drug, 100% of patients were commenced as a third line therapy, 96% of patients had a HbA1C≥7.5%, and 77% had a BMI ≥35 kg m−2. Eighty seven percent of patients had associated psychological or medical problems and 38% were started on Byetta due to occupational implications of insulin or to promote weight loss. Of those patients that continued the drug after 6 months, 60% had achieved the recommended 1% reduction in HbA1C and 89% had shown a 3% reduction in weight.

Conclusion:  After 6 months, Byetta therapy was associated with significant reductions in weight, BMI and HbA1C, which supports the findings of previous research (Buse et al., 2004; DeFronzo et al., 2005). This audit did not include a control group, and future studies could compare the outcomes of treatment with Byetta against outcomes after conventional treatment. The management of patients on Byetta followed the NICE guidance for the majority of the time. However, data for some patients was missing from ‘Diabeta’, suggesting that staff were not always recording information after each consultation with the patient. In future, a larger sample size would increase the validity of results, and future audits within the hospital could focus on record keeping.

References:  Buse J.B., Henry R.R., Han J. et al. (2004) Effects of exenatide (exendin-4) on glycaemic control over 30 weeks in sulfonylurea-treated patients with type 2 diabetes. Diabetes Care 27, 2628–2635.

DeFronzo R.A., Ratner R.E., Han J. et al. (2005) Effects of exenatide (exendin-4) on glycaemic control and weight over 30 weeks in metformin-treated patients with type 2 diabetes. Diabetes Care28, 1092–1100.

National Institute of Clinical Excellence (NICE) (2009) Type 2 diabetes newer agents (partial update of CG66). Available online from: http://guidance.nice.org.uk/CG87 [Accessed on August 2010].