Whilst lifestyle changes are the cornerstone of diabetes treatment, pharmacological therapies are usually required, not just for glycaemic control but also for cardiovascular risk management. Although therapies are launched following evidence that they show benefit to a particular facet of diabetes management (often marginal), their use in the real world often throws up major issues. These have included the impact of thiazolidendiones on CV risk, bladder malignancy and fractures, the impact of drugs acting on the GLP-1 pathway and pancreatitis and the potential link between insulin glargine and cancer (eventually dispelled). These post marketing complications only serve to cause concern to both patients and clinicians.
Whilst these concerns focus on patients who have been diagnosed with diabetes, what about the increasing number of drugs which are now linked to its development. To corticosteroids, thiazide diuretics, Beta blockers and newer anti-psychotic agents do we now need to add that cornerstone of cardiovascular protection – the statin. This issue has once again come to prominence following the publication of a population based study in the BMJ. In this study, compared with the older agent Pravastatin, an increased risk of developing diabetes was noted in those patients on more potent statins especially Simvastatin and Atorvastatin. With Rosuvastatin, an increased risk became non-significant when dose was corrected for. It is worth pointing out that the patients who are prescribed statins due to their CV risk are those at higher risk of developing diabetes in the first place and that other risk factors were not corrected for in this study. This study is in keeping with an earlier meta-analysis of 13 trials which showed a 9% increased risk of diabetes after 4 years of treatment.
Most clinicians are well aware that all drugs have side effects which must be taken into account when considering the benefits. In those patients at high risk of developing diabetes other agents exist – for example thiazides in the treatment of hypertension. However, with the use of beta blockers and especially statins to treat ischaemic heart disease, the benefits of such treatment clearly outweighs any potential risk of diabetes. In those patients with established diabetes, the impact of a marginal deterioration of glycaemic control is tiny given the benefit of these agents.
So how should this all be translated into clinical practice? Patients are increasingly knowledgeable and concerned about their conditions and potential treatments, a situation sometimes magnified by the media. Ideally this should translate into a more balanced discussion with patients as to risk/ benefit of any agent – easier said than done in a service increasingly time pressured.
Dr. Mark Freeman
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