It must certainly be related to wealth disparity, in that the more efficient formulations, and therefore more expensive formulations, are unavailable for people in lower income groups. In essence, poor people don't get the best advancements in insulin formulation and delivery.

I'd wager there's also a connection between non-white groups, as well as women, who experience discrimination bias, where doctors simply don't believe their patients. This is an ongoing problem in medicine: https://www.health.harvard.edu/blog/racism-discrimination-health-care-providers-patients-2017011611015

So the US faces the results of its capitalist and supremacist roots. It's likely yet one more reason why our quality of life and life expectancy have been dropping: https://www.cdc.gov/nchs/pressroom/nchs_press_releases/2022/20220831.htm, https://pubmed.ncbi.nlm.nih.gov/29338955/