HbA 1c in Diabetes. Case Studies Using IFCC Units

This little book is intended as an aid to all involved in diabetes care to come to terms with the change of reporting units for glycosylated haemoglobin (HbA_1c) to millimoles per mol (mmol/mol) in place of the percentage units with which all have been familiar over the past 30 or so years that routine measurement of HbA_1c in the monitoring of diabetes control has been in place. Some background information is followed by a range of clinical cases, drawing on the experience of a wide range of contributors from around the UK, and illustrating how the measurement of HbA_1c, in both ‘old’ and ‘new’ units, is used.

The book begins with the basics, even asking ‘What is Diabetes?’ and providing a brief overview. The authors then move quickly to describing the glycation process underlying the formation of HbA_1c, summarizing the evidence base for its clinical value and discussing its use in clinical practice. The need for, and the background to, the introduction of a reference method is discussed, introducing the new International Federation of Clinical Chemistry (IFCC) reporting units. A formula for conversion from percentage units is given, as are a number of ‘thermometers’ showing the relationship between HbA_1c (in both units) and various complications of diabetes. Graphs showing the relationship between HbA_1c in IFCC units with both random plasma glucose and fructosamine are also provided. Supplemental information describes methods for measurement of HbA_1c together with their limitations, particularly the presence of variant haemoglobin.

The second part of the book consists of 45 case studies of varying complexity and covering a wide range of scenarios experienced in diabetes clinics. The cases have a standard format of background, treatment plan and follow-up, and in each case, the HbA_1c value is listed in the new units with the conversion given in the margin. The varying nature of the cases presented gives a wide range of HbA_1c values and repeated comparison of units begins to give one a feel for the significance of the new values.

The book, on the one hand, by working from the basics, is an excellent educational tool for those developing experience in the field of diabetes and on the other, through its real-life illustrations, can also be beneficial to the more experienced in facilitating the transition to use of the IFCC units of reporting.