The Effect of Statin on the Incidence of Diabetes Mellitus

READERS’ COMMENTS The Effect of Statin on the Incidence of Diabetes Mellitus Navarese et al recently reported a meta-analysis of randomized controlled trials concerning the effect of various types and doses of statins on new-onset diabetes mellitus (DM). The authors concluded that pravastatin 40 mg/day was associated with the lowest risk for new-onset DM compared with placebo.1 Carter et al reported a population-based cohort study concerning the effect of various types and doses of statins on new-onset DM by setting pravastatin as a control. Although the clinical evidence was weaker than that in randomized controlled trials, these authors concluded that higher-potency statins might be contributed to the increase of new-onset DM.2 I have 2 concerns regarding Navarese et al’s study outcome. First, there were no significant differences in odds ratios versus placebo using a random-effects model, and the authors speculated as to what the potential effects in a powered head-to-head comparison would be. In their final paragraph of the Discussion, they cited a meta-analysis by Sattar et al3 and

mentioned their study limitations. Sattar et al reported that subtotal odds ratio of pravastatin on new-onset DM did not reach significance. If there is no significance in odds ratios, the potential effect of statins on DM cannot be assumed. Mizuno et al reported on the complexity of the relationship between pravastatin therapy and new-onset DM,4 and their study was cited by Sattar et al.3 The meta-analysis conducted by compiling each study should be considered with caution, although a mathematical procedure can be applied. Second, the contribution rate (weight %) of each study on the total meta-analysis cohort is informative, and it is possible for the network metaanalysis to show the contribution rate.5,6 Further studies are needed for a highquality meta-analysis to be possible. Tomoyuki Kawada, MD Department of Hygiene and Public Health Nippon Medical School Tokyo, Japan 31 May 2013

1. Navarese EP, Buffon A, Andreotti F, Kozinski M, Welton N, Fabiszak T, Caputo S, Grzesk G, Kubica A, Swiatkiewicz I, Sukiennik A, Kelm M, De Servi S, Kubica J. Meta-analysis of impact of

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different types and doses of statins on new-onset diabetes mellitus. Am J Cardiol 2013;111: 1123e1130. Carter AA, Gomes T, Camacho X, Juurlink DN, Shah BR, Mamdani MM. Risk of incident diabetes among patients treated with statins: population based study. BMJ 2013;346:f2610. Sattar N, Preiss D, Murray HM, Welsh P, Buckley BM, de Craen AJ, Seshasai SR, McMurray JJ, Freeman DJ, Jukema JW, Macfarlane PW, Packard CJ, Stott DJ, Westendorp RG, Shepherd J, Davis BR, Pressel SL, Marchioli R, Marfisi RM, Maggioni AP, Tavazzi L, Tognoni G, Kjekshus J, Pedersen TR, Cook TJ, Gotto AM, Clearfield MB, Downs JR, Nakamura H, Ohashi Y, Mizuno K, Ray KK, Ford I. Statins and risk of incident diabetes: a collaborative meta-analysis of randomised statin trials. Lancet 2010;375:735e742. Mizuno K, Tajima N, Ohashi Y, Nakamura H. Is the risk of new-onset diabetes by statins associated with diet adherence? Int J Cardiol 2013;166:277. Ades AE, Mavranezouli I, Dias S, Welton NJ, Whittington C, Kendall T. Network metaanalysis with competing risk outcomes. Value Health 2010;13:976e983. Dias S, Sutton AJ, Ades AE, Welton NJ. A generalized linear modeling framework for pairwise and network meta-analysis of randomized controlled trials. Med Decis Making 2012. http://dx.doi.org/10.1177/ 0272989X12458724 [published online ahead of print October 26].

http://dx.doi.org/10.1016/j.amjcard.2013.06.001

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