[Cardiovascular effects of insulin therapy: from pharmacology to clinical trials]

Insulin has direct effects on vascular walls which, depending on experimental models, can be either predominantly antiatherogenic or proatherogenic. In observational studies, insulin therapy is usually associated with an increase in the incidence of major cardiovascular events. However, this result is probably determined by the effect of confounders. In clinical trials performed in the acute phase of coronary syndromes, the benefits observed with insulin therapy are probably due to the improvement of glycemic control, rather than to direct effects of insulin on the cardiovascular system. In long-term trials for primary or secondary prevention such as UKPDS and ORIGIN insulin has no relevant effects on major cardiovascular events beyond those determined by the improvement of metabolic control. On the other hand, severe hypoglycemia, which is a possible side effect of insulin therapy, is associated with a worse prognosis of cardiovascular disease. The availability of new long-acting insulin analogs, which reduce the incidence of hypoglycemia for similar levels of glycemic control, makes insulin therapy easier and potentially safer for the cardiovascular system.