Science
Weight gain and diabetes threaten progress in reducing heart attacks and strokes
Researchers from the London School of Hygiene & Tropical Medicine found that decreases in three major risk factors contributed to a fall in the number of heart attacks and strokes between 1990 and 2014. However, progress in reducing numbers further has been stalled by increasing body mass index (BMI) and diabetes prevalence over the same period.
The team used Scottish health data to calculate the change in numbers of heart attacks and strokes in Scotland between 1990 and 2014. This showed that the number of heart attacks fell from 1,069 per 100,000 people to 276 per 100,000. Ischaemic strokes (a type of stroke caused by a blood clot) fell from 608 per 100,000 to 188 per 100,000 people.
Fall in heart attacks and strokes
They found that 74 per cent of this fall in heart attacks and 68 per cent of that in strokes could be accounted for by changes in risk factor prevalence. This was driven by decreases in blood pressure, cholesterol levels and smoking rates.
Average systolic blood pressure fell from 140mmHg to 129mmHg, cholesterol levels fell from 6.4mmol/L to 5.0mmol/L, and adult smoking rates more than halved from 58 per cent to 25 per cent.
Increases in BMI and diabetes prevalence
However, average BMI increased, from 27.2kg/m2 to 28.1kg/m2, and diabetes prevalence in this period in Scotland more than doubled, from 4 to 9 per cent of the population. This was estimated to lead to a 20 per cent increase in heart attacks and a 15 per cent increase in ischaemic strokes attributable to these two risk factors.
The researchers estimate that increased diabetes prevalence contributed to nearly as many heart attacks as the decline in smoking prevented.
While the team could be confident that changes in risk factors had an impact on the incidence of heart attacks and strokes, they viewed each risk factor in isolation in their analysis which means that their estimated impact is likely to be exaggerated.
The picture is similar across the UK. Figures show that the number of people being diagnosed with diabetes and developing obesity has increased over the last couple of decades. Analysis also shows that the contribution of diabetes to heart and circulatory diseases is increasing. In 1990 the number of deaths from heart and circulatory diseases associated with diabetes was 19 per cent. By 2019 this had reached 26 per cent.
Slowing progress
Our Medical Director, Professor Sir Nilesh Samani, said:
“Whilst it’s great to see the positive impact that public health measures, such as the smoking ban, have had on the number of people experiencing heart attacks and strokes over the last 25 years, it’s concerning that increasing BMI and diabetes prevalence now appear to be slowing progress.
“Obesity is a major cause of type 2 diabetes and this research highlights that the Government needs to press on with the bold pledges in the 2020 obesity strategy.
"Excess weight is a complex issue and we cannot rely on individual willpower and exercise alone to solve the problem of increasing BMI across the population. We need to address the environmental factors that drive weight gain and the development of diabetes to not lose the gains we have made in reducing the burden of cardiovascular diseases.”
This research was also supported by the Academy of Medical Sciences.