I’m heterozygous for https://www.snpedia.com/index.php/rs7903146(C;T).
So a 1.4x risk of type 2 and colon cancer.
The study is here https://www.ncbi.nlm.nih.gov/pubmed/17671651?dopt=Abstract
Essentially every T allele makes us more likely to make more glucose in our livers, and secrete less glucose stimulated insulin. The first makes us more likely to have more glucose, the second appears to protect us from making too much insulin in response. The first symptom is certainly part of type 2 diabetes. But the second is the antithesis of type 2 diabetes where we actually make too much insulin.
I suspect a series of things that all have to fall the right way to make you diabetic there is probably another series of alleles that offset this protection against high insulin - and then you have the necessary dominos in place.
BTW I am also homozygous for the second one that puts me at high risk of T1DM and about a dozen others that indicate that I am at a higher risk of autoimmune diseases. https://www.snpedia.com/index.php/rs9272346(A;A)
and the science for that is at https://www.ncbi.nlm.nih.gov/pubmed/17554300?dopt=Abstract