Cardiovascular disease in diabetes type 2: current concepts

Type 2 diabetes is a major and accelerating public health challenge. Between 1980 and 2014, a period of just 35 years, the number of adults with diabetes globally is estimated to have increased from 108 to 422 million, due not only to sharply rising obesity rates, but also to increasing population size, longer life expectancy, and rising prevalence of diabetes worldwide. Overall, worldwide age-standardized adult diabetes prevalence doubled from 4.3% to 9.0% in men and from 5.0% to 7.9% in women. The largest increases in diabetes type 2 have been demonstrated in low- and middle-income countries, whilst rises in high-income countries have been less marked, or even flat. Diabetes type 2 rates in low- and middle-income countries now in many instances surpass those in high-income countries, in response to changes in lifestyle. One factor of particular concern are the large relative increases in type 2 diabetes amongst young individuals observed in many countries, their higher overall risk factor burden, long exposure to hyperglycaemia and greater risk of complications over the life course. Type 2 diabetes is increasingly found to be a heterogeneous condition, where risk of cardiovascular disease that traditionally has been estimated at 2-4 times that of the nondiabetic population varies substantially with diabetes phenotype and accordingly diabetes does not confer the same increase in relative or absolute risk in all people. New research shows that excess risk varies substantially with type of outcome, age, glycaemic control, the presence of renal complications and other factors. Heart failure, previously less recognized that other cardiovascular conditions, is increasingly coming into focus, because of strong links with poor glycaemic control and obesity. The knowledge about risk of cardiovascular disease in diabetes is almost entirely derived from high-income countries, whereas there is comparatively very little data from low- and middle income countries, where the majority of persons with type 2 diabetes live, and where management in many cases is far from optimal. The reductions in cardiovascular disease incidence and mortality now observed in high-income countries are encouraging, because this reinforces the fact that improvement is possible and that a near-normal, or even normal life-expectancy can be achieved in subtypes of type 2 diabetes.