A claim about preventing complications is only as clear as its description of the complication. This page starts from what two named publishers say about them, for readers in Schaumburg, Illinois.
The decision and the claim
The decision is which add-ons deserve your attention, and the claim attached to each is that it heads off a complication. A PubMed Central paper on the system of care for the diabetic foot is a broader read on objectives, outcomes, and opportunities. It gives context for judging any single claim.
What the publishers describe
The American Diabetes Association says diabetes also causes blood vessels to narrow and harden, resulting in poor circulation (blood flow), another culprit when it comes to foot complications. Cleveland Clinic says diabetes-related foot complications can happen due to a snowball effect of issues: a sore or blister goes unnoticed, because neuropathy causes numbness, tingling or pain in your feet, which can make it hard to tell you have a wound.
The fine print on a snowball
Cleveland Clinic calls it a snowball effect, which describes a chain rather than one event. The two lines name different problems: numbness that hides a wound, and narrowed, hardened blood vessels. An add-on that addresses only one of them covers only part of what these lines describe.
Doing nothing extra, compared
Doing nothing extra leaves the first link in Cleveland Clinic's chain, a sore that goes unnoticed, to chance. The CDC's Tips for Healthy Feet graphic is one list of tips to set against that link, and each tip on any list should name the problem it answers.
The verdict on complication claims
Ask any add-on which of the two problems it answers. An offer that names neither needs a better reason than a headline.