HSS, I am not debating that there is some genetic component to Type I diabetes, or discounting the importance of a family medical history. In fact there is a long-term study of first-degree relatives of diabetics investigating the role that infant feeding may play in the development of Type I. The study presumes that first-degree relatives are more likely to develop diabetes, and is determining whether use of a special formula may reduce the risk.
I think I misunderstood your earlier post to imply that routine screening of first-degree relatives was the standard of care. Therefore I pointed out that routine screening of first-degree relatives of Type I diabetics is not commonly done; rather they are tested if they present symptoms.
Regarding shidduchim I agree that concern about a first-degree relative with Type I diabetes is misplaced. While Type I diabetes is serious, most people who are dating are of an age that it is unlikely that they will develop Type I if they are not already symptomatic.