Practical Classification Guidelines for Diabetes in patients treated with insulin: a cross-sectional study of the accuracy of diabetes diagnosis.
British Journal of General Practice
Royal College of General Practitioners
© British Journal of General Practice 2016. This is an OpenAccess article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
BACKGROUND: Differentiating between type 1 and type 2 diabetes is fundamental to ensuring appropriate management of patients, but can be challenging, especially when treating with insulin. The 2010 UK Practical Classification Guidelines for Diabetes were developed to help make the differentiation. AIM: To assess diagnostic accuracy of the UK guidelines against 'gold standard' definitions of type 1 and type 2 diabetes based on measured C-peptide levels. DESIGN AND SETTING: In total, 601 adults with insulin-treated diabetes and diabetes duration ≥5 years were recruited in Devon, Northamptonshire, and Leicestershire. METHOD: Baseline information and home urine sample were collected. Urinary C-peptide creatinine ratio (UCPCR) measures endogenous insulin production. Gold standard type 1 diabetes was defined as continuous insulin treatment within 3 years of diagnosis and absolute insulin deficiency (UCPCR<0.2 nmol/mmol ≥5 years post-diagnosis); all others classed as having type 2 diabetes. Diagnostic performance of the clinical criteria was assessed and other criteria explored using receiver operating characteristic (ROC) curves. RESULTS: UK guidelines correctly classified 86% of participants. Most misclassifications occurred in patients classed as having type 1 diabetes who had significant endogenous insulin levels (57 out of 601; 9%); most in those diagnosed ≥35 years and treated with insulin from diagnosis, where 37 out of 66 (56%) were misclassified. Time to insulin and age at diagnosis performed best in predicting long-term endogenous insulin production (ROC AUC = 0.904 and 0.871); BMI was a less strong predictor of diabetes type (AUC = 0.824). CONCLUSION: Current UK guidelines provide a pragmatic clinical approach to classification reflecting long-term endogenous insulin production; caution is needed in older patients commencing insulin from diagnosis, where misclassification rates are increased.
This study was funded by (the previously existing) NHS Diabetes, with direct funding from the Department of Health (DoH), and the National Institute for Health Research (NIHR) under its Research for Patient Benefit programme (PB-PG-0711-25111). Andrew T Hattersley is an NIHR and Wellcome Trust senior investigator. Beverley M Shields, Suzy V Hope, Andrew T Hattersley, Bea A Knight, Maggie Shepherd, and Sophie M King are supported by the NIHR Exeter Clinical Research Facility. NIHR has supported Suzy V Hope and Angus G Jones through academic clinical fellowships, and Angus G Jones through a doctoral research fellowship and clinical lectureship. Richard A Oram was supported by Diabetes UK through a doctoral research fellowship. Kamlesh Khunti is an NIHR senior investigator, and acknowledges support of the NIHR Collaboration for Leadership in Applied Health Research and Care East Midlands; he is also an advisor to the DoH’s NHS Health Checks programme. The views given in this article do not necessarily represent those of the NIHR, the NHS, or the DoH.
This is the final version of the article. Available from Royal College of General Practitioners via the DOI in this record.
Vol. 66 (646), op. e315-e322
Except where otherwise noted, this item's license is described as © British Journal of General Practice 2016. This is an OpenAccess article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.