Are European standard deviation targets for haemoglobin A1c too strict?
✍ Scribed by Kilpatrick, E.S.; Kilpatrick, W.S.; Dominiczak, M.H.; Small, M.
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 125 KB
- Volume
- 15
- Category
- Article
- ISSN
- 0742-3071
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✦ Synopsis
The Diabetes Control and Complications Trial (DCCT) has provided objective evidence for desirable glycaemic control in Type 1 patients and defines the benefits of good glycaemic control in terms of haemoglobin A 1c (HbA 1c ) values. However, HbA 1c assays vary, leading to suggestions that glycaemic control be classified according to numbers of standard deviations (SD) from a local non-diabetic population mean. We have classified the glycaemic control of 339 UK Type 1 diabetic patients (182 male, 157 female, median age 36 (range 15-74) years) using the DCCT to set HbA 1c targets and compared this with the SD method. Using age matched controls (mean HbA 1c 4.02 %, SD 0.28 %, n = 106), SD guidelines classified 1 % of patients into good (HbA 1c Ͻ3SD from reference mean), 4 % into borderline (3-5SD) and 95 % into poor (Ͼ5SD) glycaemic control. When calibrating the same instrument to the DCCT analyser (r = 0.996), 37 % of patients had HbA 1c results lower than the 7 % median value found in the intensively treated DCCT group, while only 12 % of patients had values greater than the 9 % conventionally treated median HbA 1c . DCCT subjects with HbA 1c values of less than 8 % belonged predominantly to the intensively treated group. In this study, 71 % of patients fell into this category. Thus, guidelines based on numbers of SD away from a non-diabetic mean may overestimate the glycaemic control required to reduce microvascular complications in Type 1 patients. Standardizing to DCCT targets is more appropriate.