The claim that eating dark chocolate daily reduces the risk of diabetes has a bit of support backing it up, however I feel that it requires more context and deliberation. Firstly, the source listed in the initial claim is from Good Morning America, which is not the most trustable source of information, especially when it comes to scientific findings in relation to the health of millions of people. However, there is a link to the original Journal publication from the study included within the GMA article, where information from three studies was compiled in order to reach their conclusions over the impacts of chocolate intake on type 2 diabetes. It is important to note that, even in this publication, it is stated that further studies need to be done to confirm the information in the study, as "associations between chocolate consumption and risk of T2D remain controversial owing to inconsistent findings in observational studies." It is also important to note that some of the data collected by any of the three studies compiled by this publication is nearly 40 years old, with two beginning in 1986 and the other beginning in 1987. A 2022 publication, detailing a study done by three researchers from the University of British Columbia, discussed the results of the consumption of sugar-free or conventional dark chocolate on lower blood glucose within adults with diabetes. Within this study, they found that eating sugar-free dark chocolate, led to a lower blood glucose as compared to that of conventional dark chocolate, however longer-term effects still require further determination. Dark chocolate could still have an effect over the blood glucose levels of individuals with diabetes, especially as the level, or amount, of sugar and/or milk contained within dark chocolates varies.
This is not to completely disregard any of the health effects dark chocolate can have, as it truly can aid with insulin sensitivity, improve vascular function, serves as an antioxidant, and can act in several more roles. It is incredibly beneficial, and is a great addition to one's diet. However, there is not enough information on the long-term effects of dark chocolate consumption in relation to the prevention of diabetes or aiding those with diabetes, especially in the amounts this claim promotes.
Sources:
https://www.bmj.com/content/387/bmj-2023-078386
https://journals.sagepub.com/doi/full/10.1177/11786388221076962
https://www.researchgate.net/profile/Arvind-Singh-21/post/Do_you_like_dark_Chocolate_Is_it_harmful_to_the_body/attachment/5b648bf74cde265cb653bcb5/AS%3A655588992229380%401533316004363/download/1.pdf
