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Could sugar be the cause of type 2 diabetes?

Nov 23, 2016

“Is sugar toxic? Could it be the cause of type 2 diabetes?” In order to answer this question, we must define “toxic”, which is “the degree to which a substance can damage an organism”. In order to demonstrate toxicity, sugar must be an independent risk factor for diabetes, irrespective of its caloric content or its effects on obesity. Also, causation must be shown; correlation is not enough.

Prospective correlation studies, such as Yang et al. in 2014 demonstrated increased cardiovascular mortality over two decades based on the percent of calories in the diet as added sugar, and adjusting for weight. The EPIC-Interact Study in 2013 demonstrated that after adjusting for energy intake and weight, each sugar-sweetened beverage per day increased risk for diabetes by 29%. Imamura et al. in a systematic review in 2015 showed that sugared beverage (including juice) consumption was correlated over time with an increased risk for diabetes. Econometric analysis by Basu et al. in 2013 demonstrated that every 150 extra calories per day globally did increase prevalence of diabetes (0.1%), yet if those 150 calories were sugar instead, there was an 11-fold increased prevalence of diabetes (1.1%), unrelated to calories or obesity. Most recently, our group has addressed causation, performing an isocaloric glucose-for-fructose exchange for 10 days in 43 children with metabolic syndrome. We demonstrated improvements in virtually all aspects of metabolic health (insulin sensitivity, glucose tolerance, triglycerides, HDL, liver fat, visceral fat) exclusive of caloric content or weight change.

Conversely, meta-analyses of studies substituting fructose for glucose show no inconclusive effects on body weight, glucose tolerance or haemoglobin A1c, liver fat, or lipid levels, except at extremely high dose. These meta-analyses cast doubt on the role of sugar as a potential causative mechanism.

How to rationalise these differences? What is the real truth? What does the science say? Can Type 2 diabetes be prevented? What happened to the Food Pyramid? What has been the industry’s role? How do the recent advances in nutrition alter patient care and public health going forward? Can these changes be accommodated within the current medical framework, or does medicine have to change? What about sugar taxes? What will be industry’s role in the future?

Information about the discussion leader

The discussion will be moderated by Robert H. Lustig, Professor of Pediatrics, Division of Endocrinology, Member of the Institute for Health Policy Studies, University of California, San Francisco School of Medicine 




3. Lustig RH: Sickeningly sweet: Does sugar cause diabetes? YES. Can J Diabetes 40:282-286, 2016.

4. Sievenpiper JL: Sickeningly sweet: Does sugar cause diabetes? NO. Can J Diabetes 40:287-295, 2016.