50 years forward: mechanisms of hyperglycaemia-driven diabetic complications

The advent of insulin treatment in 1923 meant fewer diabetes deaths from acute metabolic deterioration and sepsis and a progressive increase in the burden of disease caused by end-organ damage. These diabetic complications are the major cause of morbidity and premature mortality among diabetic subjects. Over the last 50 years it has become apparent that diabetic complications in disparate tissues may result from a combination of common pathological processes. Pathways activated by initial metabolic insults are promoted by co-factors such as renin–angiotensin–aldosterone system activation, hyperinsulinaemia, underlying genetic susceptibility, and traditional vascular risk factors, particularly hypertension and lipids. These common pathways include AGE formation, reactive oxygen species overproduction, protein kinase C activation, mitochondrial dysfunction and activation of proinflammatory and profibrotic signalling cascades. Once established, these interlinked pathways become self-perpetuating. Many drugs acting against individual downstream targets in these pathways have failed due to lack of efficacy or adverse effects. Gains in the future may be made by better control of existing risk factors, more sophisticated modulation of tissue glucose and insulin signalling, and interventions to improve mitochondrial function and reduce oxidative stress. Epigenetic and microRNA research may lead to methods to disrupt the mechanisms whereby pathological pathways are perpetuated. Expansion in capacity and expertise in biomarker measurement and analysis may allow better targeting of therapies to patients who are most likely to benefit. This is one of a series of commentaries under the banner ‘50 years forward’, giving personal opinions on future perspectives in diabetes, to celebrate the 50th anniversary of Diabetologia (1965–2015).