While I will defer to your experience with working with addicts, with respect I would suggest that the nature of your work may lead you to underestimate the addictive properties of sugar.
I am not claiming it compares with alcohol, meth, or crack cocaine addiction, but I think it is not unreasonable to compare its intensity to, say, coffee addiction. Except that in the case of sugar, the consequences can be chronic disease and premature death.
Research shows that sugar affects the brain reward pathways in a way similar to other drugs [1]. This contributes to its addictive properties in addition to those caused by the metabolic disruptions brought about by insulin resistance.
[1] https://www.ncbi.nlm.nih.gov/pubmed/23719144
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2235907/
[3] https://addictionresource.com/addiction/sugar-addiction/