Consensus meeting on reporting glycated haemoglobin and estimated average glucose in the UK: time for ‘Kilpatrick's Kludge’?

The Consensus meeting on reporting glycated haemoglobin (HbA1c) and estimated average glucose (eAG) in the UK has recommended that HbA1c continues to be reported in NGSP (synonymous with DCCT) units and also include values in the new IFCC units of mmol/mol. ¹ Table 1 gives the IFCC equivalent to the current DCCT results. Central to the acceptance and adoption of IFCC units will be the task of becoming familiar with the new numbers involved. As someone who still has difficulty in relating Fahrenheit and Celsius measurements in weather forecasts, a simple means of converting DCCT to IFCC units would be of great help in this regard.

Table 1

Conversion of DCCT to IFCC HbA1c values

HbA1c (%) DCCT	HbA1c (mmol/mol) IFCC
4	20
5	31
6	42
7	53
8	64
9	75
10	86

In a posting on the Association for Clinical Biochemistry mailbase in January 2008 entitled ‘Middle's Manipulation’ (http://www.jiscmail.ac.uk/cgi-bin/webadmin?A1=ind0801&L=acb-clin-chem-gen), Jonathan Middle described his simplified means of converting from DCCT to IFCC units thus:

Still being too complicated for me, I replied with ‘Kilpatrick's Kludge’. Known as ‘minus 2 minus 2’, if the DCCT HbA1c is, say, 9%, the IFCC HbA1c is nine minus two (7) minus two (5) = 75 mmol/mol. Table 1 shows that this works for other round DCCT numbers and indeed all of those from 4% to 13%, both inclusive.

The UK consensus statement concluded that an extensive education programme should be developed urgently for all health-care professionals and people with diabetes to help in the understanding and interpretation of the new IFCC units. ¹ Hopefully, these manipulations and kludges will help make that task a little easier.