Frequency of blood glucose monitoring in relation to glycaemic control: observational study with diabetes databaseBMJ 1999; 319 doi: https://doi.org/10.1136/bmj.319.7202.83 (Published 10 July 1999) Cite this as: BMJ 1999;319:83
All rapid responses
We were interested to read the study by Evans et al. (BMJ 1999; 319:
83-86), in which data from a diabetes register were used to assess the
relationship between use of glucose
monitoring strips and blood glucose control. We have some concerns about
the validity of their conclusions.
The authors rightly allowed for a number of confounding factors.
However, there may be many other differences between those using and not
using the strips, which could explain the differences in glucose control
observed. These include: intensity of insulin regime; frequency of follow-
up and attendance; compliance with treatment and diets; and place of care
(GP, hospital outpatients, or shared care).
Even assuming that the differences in blood glucose control observed
were not due to confounding factors, a problem of generalisability and
possible selection bias remain. The
subjects were a highly selected group: 790/5601 type II diabetics were
considered eligible (with selection criteria not stated), and only 258
type I and 290 type II diabetics with a recorded glycated haemoglobin
concentration were included. Hence the findings may not apply to other
diabetics on the register
We believe these findings from such observational studies should be
treated with great caution and given the limitations it is unsafe to
conclude that self-monitoring improves control. Evidence from more
rigorous studies is required.
Stephen Metcalfe BMedSci (Hons)
Peter Yeates BMedSci (Hons)
3rd Year Medical Students
Department of Epidemiology & Public Health, The Medical School,
University of Newcastle upon Tyne
Competing interests: No competing interests