Healthy people with impaired beta cell function – the cells in the pancreas that secrete insulin – have three times the risk of developing diabetes or pre-diabetes and double the risk of abdominal obesity over a three-year period compared to those whose cells are functioning normally, according to results from a major pan-European study reported today at the European Association for the Study of Diabetes (19 September, Amsterdam).
The RISC (Relationship between Insulin Sensitivity and Cardiovascular risk) study is the largest prospective, observational study of healthy people to explore the role of insulin resistance in the deterioration of diabetes and cardiovascular risk markers. It recruited more than 1500 middle-aged, healthy individuals from 14 European countries, who are undergoing regular monitoring for insulin resistance and other cardiovascular risk factors, including obesity, blood pressure, lipid levels and physical activity.
Preliminary data from three-year follow-up of 784 participants (mean age at baseline 48 + 8 years) showed that insulin resistance was not the sole underlying driver of cardiometabolic risk as had been previously thought. Instead, insulin resistance, obesity, central obesity and a high insulin response each made independent, partial contributions to the development of Insulin Resistance Syndrome or Metabolic Syndrome. At three years, 1% of the initially healthy individuals had developed diabetes, 3% had impaired fasting glucose and 12% had impaired glucose tolerance.
The results revealed the importance of total accumulated physical activity (a combination of moderate exercise, such as jogging, everyday activities such as walking and extent of sedentary behaviour) as a key driver of insulin sensitivity. Physical activity was associated with better insulin sensitivity even in people with abdominal obesity. It also reduced the age-related stiffening of the arterial wall.
Reporting the findings, Mark Walker, professor of molecular diabetes, University of Newcastle-Upon-Tyne, and consultant endocrinologist, Newcastle Hospitals Acute Trust, UK, said: “The key message to clinicians is to encourage all patients, including healthy people, to keep physically active. Preventing obesity and encouraging physical activity will promote cardiometabolic health.” He added: “The benefits of physical activity include a decrease in age-related arterial stiffness, as well as some compensation for being overweight or obese.” Longer term follow up of RISC participants will assess whether these benefits translate into cardioprotective effects.
The benefit of physical activity appeared to increase with greater activity and was not mediated by its influence on cardiovascular risk factors such as blood pressure, central obesity, plasma lipids and insulin levels. Professor Walker suggested that physical activity improved insulin action at a molecular level by increasing the cellular uptake of glucose. He suggested that the RISC results added to previous research showing that lifestyle changes, including physical activity, significantly reduce the risk of developing diabetes in those at risk by demonstrating that they can also reduce the risk in the healthy population.
The RISC study is being co-ordinated by the European Group for the Study of Insulin Resistance and is sponsored by the European Union and AstraZeneca.
43rd Annual Meeting of the European Association for the Study of Diabetes
Written by: Susan Mayor PhD, freelance medical journalist
Email: mayor at dircon.co.uk