Diseases of the heart and blood vessels account for approximately 70% of all mortality in people with diabetes. Compared to their non-diabetic counterparts the relative risk of mortality caused by disorders of the heart and blood vessels is two to three for men and three to four for women with diabetes. Type 2 diabetes is mainly characterised by a reduced ability of the hormone insulin to stimulate glucose uptake in body fat and muscles (insulin resistance) and affects most people suffering from diabetes. Several medications are on the market to treat diabetes, amongst them rosiglitazone as a member of the 'glitazones' reduced risk markers for diseases of the heart and blood vessels. Since the two biggest trials in people with type 2 diabetes showed that improved blood glucose alone is not enough to reduce the risk of the above mentioned diseases we looked for longer-term studies investigating 24 weeks as a minimum of rosiglitazone treatment on patient-oriented outcomes. As patient-oriented outcomes we defined mortality, complications of diabetes, side effects of the medication, health-related quality of life, costs and metabolic control (lowering of blood glucose to near normal levels).
Eighteen trials randomised 3888 people to rosiglitazone therapy. The longest duration of rosiglitazone treatment was four years, most trials lasted around half a year. Unfortunately, the published studies of at least 24 weeks rosiglitazone treatment in people with type 2 diabetes mellitus did not provide relevant evidence that patient-oriented outcomes are positively influenced by this agent. The chance of developing oedema was approximately doubled, the risk of cardiovascular diseases increased. The single large randomised controlled trial showed evidence of raised cardiovascular risk after rosiglitazone treatment. Moreover, new safety data show increased numbers of broken bones in women. This finding was published years after approval of this agent by drug regulatory authorities. New ways of exploring drug effects, for example by early long-term studies in many people, as well as public access to all safety data of published and unpublished investigations have to be established.