New-onset diabetes and antihypertensive treatment.

Introduction: Chronic diseases substantially contribute to the continuous increase in health care expenditures, including type-2 diabetes mellitus as one of the most expensive chronic diseases. Arterial hypertension presents a risk factor for the development of type-2 diabetes mellitus. Numerous analyses have demonstrated that antihypertensive therapies promote the development of type-2-diabetes mellitus. Studies indicate, that the application of angiotensin converting enzyme (ACE) inhibitors and angiotensin-receptor-blockers (ARB) lead to less new-onset diabetes compared to beta-blockers, diuretics and placebo. Given that beta-blockers and diuretics impair the glucose metabolism, the metabolic effects of different antihypertensive drugs should be regarded; otherwise not only the disease itself, but also antihypertensive therapies may promote the development of new-onset diabetes. Even though, the cost of ACE inhibitors and ARB are higher, the use in patients with metabolic disorders could be cost-effective in the long-term if new-onset diabetes is avoided.

Objectives: To evaluate which class of antihypertensive agents promote the development or the manifestation of type-2 diabetes mellitus. How high is the incidence of new-onset diabetes during antihypertensive therapy and how is treatment-induced type-2 diabetes mellitus evaluated clinically? Which agents are therefore cost-effective in the long term? Which ethical, social or legal aspects should be regarded?

Methods: A systematic literature review was conducted including clinical trials with at least ten participants which reported new-onset diabetes in the course of antihypertensive treatment. The trials had to be published after 1966 (after 2003 for economic publications) in English or German.

Results: A total of 34 clinical publications meet the inclusion criteria. Of these, eight publications focus on the development of diabetes mellitus under treatment with diuretic and/or beta-blockers, six publications focused on ACE inhibitors alone or in combination with calcium-channel-blockers, ten publications on ARB and/or ACE inhibitors with respect to their effects on new-onset diabetes or their preventive aspects. Furthermore, five publications investigate the role of calcium-channel-antagonists in the development of diabetes, and five publications indicate the development of new-onset diabetes with different antihypertensive agents amongst each other or in comparison to no antihypertensive treatment. The clinical trials show a significant difference in the development of new-onset diabetes. Therapies with diuretics and/or beta-blockers result in a higher incidence of new-onset diabetes. ARB as well as ACE inhibitors have a preventive effect and calcium-channel-blockers show a neutral position regarding the development of new-onset diabetes. Two publications report on economic results. The first one evaluates the cost-effectiveness of ARB alone or in combination with calcium-channel-blockers in comparison to diuretics alone or in combination with beta-blockers. The second publication compares economic outcomes of calcium-channel-blockers and beta-blockers considering the development of new-onset diabetes. Treatment with the ARB candesartan lead to savings in total costs of 549 US-Dollar per patient and in incremental costs of 30,000 US-Dollar per diabetes mellitus avoided. In the second publication, costs to the amount of 18,965 Euro in Great Britain and 13,210 Euro in Sweden are quoted for an avoided event. The treatment with calcium-channel-blockers compared to beta-blockers is proven to be more cost-effective. No publications were identified regarding ethical, social and legal aspects.

Discussion: The available meta-analyses allow for a high clinical evidence level. A few studies vary in terms of diabetes definition and study duration. In most of the trials, the incidence of new-onset diabetes is not an endpoint. The evaluation of treatment-induced diabetes mellitus cannot be conducted, due to the lack of sufficient results in the identified literature. The two economic studies do not address all the objectives sufficiently. Ethical, social and legal aspects are discussed but not analysed systematically.

Conclusion: Based on these studies, sufficient evidence to confirm the presumption that diuretics and/or beta-blockers promote the development of new-onset diabetes compared to other antihypertensive agents, especially in patients who are predisposed, is presented with this report. Trials reflecting the clinical relevance of treatment-induced diabetes mellitus compared to existing diabetes mellitus regarding cardiovascular outcomes are required. Also health economic evaluations considering the development of new-onset diabetes should be conducted for the different classes of antihypertensive agents.