Glitazones have been introduced as second-step medication for type 2 diabetics, and today
rosiglitazone and
pioglitazone are blockbuster drugs. However,
glitazones may have important adverse effects that outweight their beneficial effect on
insulin resistance and glycemia. The larger trials have shown that
glitazones produce a
weight gain of 4-5 kg over 3-4 years of treatment, and the
weight gain cannot be explained by fluid retention. Moreover, the risk of
myocardial infarction is increased by 43% by
rosiglitazone, and there are clear indications of increased risk of
heart failure. Furthermore, there are studies to suggest that
glitazones also increase the risk of fractures, whereas an increased
cancer risk is not supported. In conclusion, given the increased cardiovascular risk, and that a
weight gain of few kg can increase risks of
cancer of the breast, colon, prostate and endometrium, the use of
glitazones should be questioned. There is a need for more safe and weight neutral drugs to treat
type 2 diabetes.