Does eating too much sugar cause type-2 diabetes? The answer has always been "not directly", that is, too much sugar, commonly consumed along with too much unhealthy food, causes weight gain, which contributes to diabetes. But the 2013 article by the UC San Francisco researchers, The Relationship of Sugar to Population-Level Diabetes Prevalence: An Econometric Analysis of Repeated Cross-Sectional Data, is said to give a positive answer to the question. According to news articles such as Quantity of Sugar in Food Supply Linked to Diabetes Rates, and High Sugar Consumption Linked To Type 2 Diabetes, the author of the research article said that “in medicine, we rely on the postulates of Sir Austin Bradford Hill to examine associations to infer causation, as we did with smoking. You expose the subject to an agent, you get a disease; you take the agent away, the disease gets better; you re-expose and the disease gets worse again. This study satisfies those criteria, and places sugar front and center.”
Unfortunately, I can't find much talk about this research on the Internet, especially some time after its publication. Six years have passed and the public opinion on whether there is relationship between sugar intake and diabetes largely remains negative. An 2017 article summarizes various studies, with a general conclusion of "No" to the title question "Does Sugar Cause Diabetes?", citing 16 references, without mention of the 2013 UCSF article.
[2019-11 Update] According to a new article Changes in Consumption of Sugary Beverages and Artificially Sweetened Beverages and Subsequent Risk of Type 2 Diabetes: Results From Three Large Prospective U.S. Cohorts of Women and Men, "[i]ncreasing consumption of sugary beverages or ASBs was associated with a higher risk of type 2 diabetes, albeit the latter may be affected by reverse causation and surveillance bias." Dr. Weil calls the study "the first to investigate whether or not changes in beverage choice and long-term consumption of sugar or artificially sweetened drinks is associated with the risk of type 2 diabetes."
