This article has been Editor—In their editorial Venkat Narayan et al make a case for the American Diabetes Association's recommendation to screen for pre-diabetes in people over 45.1 Pre-diabetes is defined as either impaired glucose tolerance (two hour glucose concentration 7.8-11
mmol/l after a glucose load) or an impaired fasting glucose concentration of 6.1-6.9mmol/l. Those screening positive are at high risk of cardiovascular diseases and diabetes and therefore would be counselled on weight loss and increasing physical activity.
mmol/l after a glucose load) or an impaired fasting glucose concentration of 6.1-6.9mmol/l. Those screening positive are at high risk of cardiovascular diseases and diabetes and therefore would be counselled on weight loss and increasing physical activity.This recommendation has profound implications for the health care of South Asian populations originating in the Indian subcontinent living in urban settings where pre-diabetes is common.2
We reported a secondary analysis of the Newcastle heart project based on age and sex adjustment using the standard population of England and Wales on the prevalence of diabetes and pre-diabetes in those aged 25-74 of South Asian (n=680), Chinese (n=375), and white European origin (n=824). Weighted percentages and unweighted numbers for South Asians show that the prevalence of impaired fasting glucose (138/680) and impaired glucose tolerance (140/680) was 19%.3 The prevalence of pre-diabetes on either definition was 30.5% (226/680). The prevalence of diabetes based on two hour glucose measures was 20.1% (160/680); on the American criteria, 21.4% (173/680); and on either, 23.4% (189/680). Only 49% (295/680) of the population had normal glucose tolerance. A programme of care for pre-diabetes would be needed for about half of the South Asian population in the 25-74 age group, a formidable task complicated by issues discussed below.
Narayan et al would prioritise screening in those with a body mass index of 25 or more, a marker of excess adipose tissue. Markers of obesity, including body mass index, do not have equivalence across ethnic groups.4 South Asians in the United Kingdom have slightly lower indices but higher waist:hip ratios and greater skinfold thicknesses. Body mass index is not a good indicator of adiposity in South Asians, and a lower cut-off point for being overweight is necessary.
If interventions are to work people need to perceive risk and benefits accurately. In the Newcastle heart project, South Asian women's perceptions of their own weight did not match guidelines on being overweight and obese.5 A substantial proportion of overweight South Asian women perceived themselves to be of normal weight, but women of European origin had the opposite problem. South Asians' knowledge of the causation and prevention of diabetes and heart disease in nearby South Tyneside was poor.
Finally, lack of physical exercise poses a huge challenge (reference available at bmj.com/cgi/eletters/325/7361/403#25585). Although the task of halting the process of pre-diabetes becoming diabetes is urgent, careful evaluation of screening and interventions is essential.