PPARS, insulin resistance and type 2 diabetes.
It is clear that the PPAR receptors are exciting targets for therapeutic compounds likely to impact on insulin sensitivity, lipid and glucose homeostasis and vascular disease. The PPARgamma receptor agonists rosiglitazone and pioglitazone are very useful additions to the treatment options for type 2 diabetes. Currently they have limited licences, particularly in Europe, and hopefully as further clinical trial data becomes available these will be extended. Clinical outcome studies are important to ensure that the surrogate effects on glucose and other parameters translate into improved outcomes. There is exciting potential for these agents with the possibility of a combination of effects not only on glucose and lipid homeostasis but also on coagulation and thrombosis, blood pressure and microalbuminuria, which are likely to impact on vascular disease. If the current lack of evidence of serious hepatic toxicity persists they have an advantage over metformin in terms of tolerability and can be used in patients with impaired renal function. In addition to potential effects on diabetic outcome it will be of tremendous interest to determine whether these compounds, which improve insulin sensitivity and beta-cell function, will impact on the natural history of the disease. From what is known of the PPAR receptor systems it is likely that compounds acting as agonists or partial agonists for these receptors will have differing effects and it is possible to envisage the tailoring of compounds to enhance wanted effects and diminish unwanted effects, particularly fluid retention and weight gain. The future certainly looks exciting in this area.