Such claims are based on a small randomised, controlled, cross-over trial of 13 healthy men receiving either a high-sugar diet (providing 25 per cent of their energy) or a diet providing 10 per cent of their energy as sugar for 6 weeks (about average for a British adult).
The researchers, from the Belfast's Royal Victoria Hospital and Queen's University, report in the American Diabetes Associations journal Diabetes that no significant difference in the measures of insulin resistance was observed between the groups.
"Sugar has traditionally been linked to the development of diabetes. These findings challenge that thinking, and show that intakes of more than double that currently recommended do not appear to have an adverse effect on markers of diabetes risk," said lead researcher Steven Hunter from the Royal Victoria Hospital in Belfast.
Classed as an epidemic by the World Health Organisation, at least 171m people worldwide suffer from diabetes, a figure likely to more than double to 366m by 2030. The American Diabetes Association estimates that at least 90 per cent of the 17m Americans diagnosed with diabetes have type 2.
The researchers set out to test guidelines for the healthy population that advise a restriction in sucrose intake, and assigned the men (average age 33, average BMI 26.6 kg per sq.m) to sequential 6-week dietary interventions separated by a 4-week washout period.
The equal calorie diets were prepared to have approximately the same carbohydrate, fat and protein content, with the only difference being that sucrose was used in place of starch. The high sucrose diet contained, on average, 200g per day while the low sucrose diet contained 80g of sucrose.
Dr. Hunter measured insulin resistance with a two-step glucose clamp, said to be the research 'gold standard'.
Writing in Diabetes, Dr. Hunter and his co-workers report that no weight changes were recorded for either group, and that there was no significant differences in glucose uptake and production. Additionally, no significant adverse effects for a number of other metabolic and physiologic parameters were observed between the groups, he said, such as elasticity of the arteries, and glycaemic profiles.
"In this study, a high-sucrose intake as part of an eucaloric, weight-maintaining diet had no detrimental effect on insulin sensitivity, glycaemic profiles, or measures of vascular compliance in healthy non-diabetic subjects," said the researchers.
"It is likely that other dietary factors such as excess calories and lifestyle factors such as physical inactivity and weight gain may be more important than carbohydrate type," said Hunter.
A spokesperson for British Charity Diabetes UK told FoodNavigator.com that a high sugar intake does not, in itself cause diabetes, but stressed that it can be a contributing factor to weight gain and obesity.
"Being overweight, especially around your middle, is a risk factor for Type 2 diabetes. Diabetes UK would recommend everyone eat a healthy, balanced diet and do at least 30 minutes of physical activity 5 days a week, to reduce their risk of diabetes and other health problems." said the charity.
Volume 55, Pages 3566-3572, doi: 10.2337/db06-0220
"Effect of eucaloric high- and low- sucrose diets with identical macronutrient profile on insulin resistance and vascular risk; A randomised controlled trial"
Authors: R.N. Black, M. Spence, R.O. McMahon, G.J. Cuskelly, C.N. Ennis, D.R. McCance, I.S. Young, P.M. Bell, S.J. Hunter