Sugar may have a direct link to diabetes, according to a large epidemiological study by the University of California San Francisco (SCSF). Scientists previously thought sugar indirectly contributed diabetes by contributing to obesity, which is a risk factor for diabetes. Their study was published on Feb. 27, 2013 in PLOS ONE.
Researchers analyzed diabetes rates and global sugar data from 175 countries over the last decade and took into account obesity rates and other diabetes risk factors. Researchers found that an increase in sugar consumption was linked to higher diabetes rates.
“It was quite a surprise,” said Sanjay Basu, MD, PhD, an assistant professor of medicine at the Stanford Prevention Research Center and the study’s lead author. The research was conducted while Basu was a medical resident at UCSF and worked with Robert Lustig, MD, a pediatric endocrinologist at UCSF Benioff Children’s Hospital and the paper’s senior author.
“We’re not diminishing the importance of obesity at all, but these data suggest that at a population level there are additional factors that contribute to diabetes risk besides obesity and total calorie intake, and that sugar appears to play a prominent role.”
The study found that for every additional 150 calories of sugar available per person per day, the population’s diabetes rate went up one percent irregardless of variations in physical activity, calorie counts, and other economic variables. In contrast, 150 calories from other sources only caused a 0.1 percent increase in the population’s diabetes rate.
Researchers looked at possible alternate explanations for a link between sugar and diabetes such as:
- Obesity
- Non-sugar elements in foods such as fruit, fiber, meat, oils and cereals
- Total calories available each day
- Sedentary lifestyle
- Economic development rates
- Household income
- Population urbanization
- Tobacco and alcohol use
- The percentage of people 65 years of age and older, as there is a link between diabetes risk and age
Researchers used food availability data instead of consumption data because there are no large international databases that directly measure food consumption.
The study also found that the longer people are exposed to excess sugar, the higher the population’s diabetes rates rise, even after controlling obesity and other factors. When sugar availability dropped, diabetes rates dropped no matter what changes had been made in dietary intake or physical activity.
“As far as I know, this is the first paper that has had data on the relationship of sugar consumption to diabetes,” said Marion Nestle, PhD, a professor of nutrition, food studies and public health at New York University who was not involved in the study. “This has been a source of controversy forever. It’s been very, very difficult to separate sugar from the calories it provides. This work is carefully done, it’s interesting and it deserves attention."
"The fact that the paper used data obtained over time is an important strength," Basu said. “Point-in-time studies are susceptible to all kinds of reverse causality,” he said. “For instance, people who are already diabetic or obese might eat more sugars due to food cravings.”
Basu emphasized that the findings do not prove that sugar causes diabetes, but supports previous research that sugar affects the pancreas and liver in ways that obesity and diet does not. “We really put the data through a wringer in order to test it out,” Basu said.
“As far as I know, this is the first paper that has had data on the relationship of sugar consumption to diabetes,” said Marion Nestle, PhD, a professor of nutrition, food studies and public health at New York University who was not involved in the study. “This has been a source of controversy forever. It’s been very, very difficult to separate sugar from the calories it provides. This work is carefully done, it’s interesting and it deserves attention."
Basu says that more studies are needed to affirm a possible cause-and-effect connection between diabetes and sugar consumption.
