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Br J Gen Pract. Jul 1, 2010; 60(576): 534.
PMCID: PMC2894388
Authors' response
Gijs Landman
Internal Medicine, Isala Clinics, PO BOX 10400, Zwolle, 8000 GK, the Netherlands. E-mail: g.w.d.landman/at/isala.nl
Kornelis van Hateren
Diabetes Centre, Isala Clinics, the Netherlands
Nanne Kleefstra
Diabetes Centre, Isala Clinics, the Netherlands
Henk Bilo
Diabetes Centre, Isala Clinics, the Netherlands
In our article, published in the March edition of this journal, we state that ‘it may be better to focus on other risk factors, such as smoking, high blood pressure, and lipid profile disturbances, than to aim for increasingly lower therapeutic values for HbA1c.’1 The validity of our conclusions was confirmed by a recently published large retrospective study.2 Although the design was different, it emphasised the absence of benefit of strict glycaemic control in patients with longer diabetes duration. In fact, this study even showed an increased mortality in patients with HbA1c under 7.5% who underwent treatment intensification with insulin.
In his comment to our article, Searle points out that there are no baseline differences in these risk factors between the survivors and the deceased in our study.3 Although this observation is correct, we respectfully disagree that it contradicts our statement. Absence of differences in baseline characteristics, for example smoking, does not mean that smoking is not an independent risk factor for mortality. To answer the question whether smoking, blood pressure, and cholesterol levels are related to mortality, Cox regression analyses, including correction for confounders, are an option in order to better interpret a (possible) effect of, in this case, HbA1c on mortality. For example, in the same study cohort, we studied the relationship between mortality and lipid profile in different age groups.4 In this study, higher cholesterol levels did relate to mortality.
We agree with Searle that the benefits of interventions, as studied in randomised controlled trials, do not necessarily translate to improvements in daily practice. Many trials include a selected population and are, therefore, not representative of the general population. However, our results more or less confirm the results of these trials, like the UKPDS, that we discussed in our article.
REFERENCES
1. Landman GW, van Hateren KJ, Kleefstra N, et al. The relationship between glycaemic control and mortality in patients with type 2 diabetes in general practice (Zodiac–11) Br J Gen Pract. 2010;60(572):172–175. [PMC free article] [PubMed]
2. Currie CJ, Peters JR, Tynan A, et al. Survival as a function of HbA1c in people with type 2 diabetes: a retrospective cohort study. Lancet. 2010;375(713):481–489. [PubMed]
3. Searle A. Glycaemic control and mortality. Br J Gen Pract. 2010;60(576):353.
4. Van Hateren KJ, Landman GW, Kleefstra N, et al. The lipid profile and mortality risk in elderly type 2 diabetic patients: a ten-year follow-up study (ZODIAC–13) PLoS One. 2009;4(12) : e8464. [PMC free article] [PubMed]
Articles from The British Journal of General Practice are provided here courtesy of
Royal College of General Practitioners