The Nazis only euthanized people who were permanently institutionalized in state hospitals, and they only sterilized people who were on a limited list of conditions:

(1) Congential Mental Deficiency,

(2) Schizophrenia,

(3) Manic-Depressive Insanity,

(4) Hereditary Epilepsy,

(5) Hereditary Chorea (Huntington's),

(6) Hereditary Blindness,

(7) Hereditary Deafness,

(8) Any severe hereditary deformity.

I haven't seen anything that indicates they considered diabetes to be any of the above, or targeted people with diabetes to any degree (at most, there were Nazi doctors who argued that Jews were more likely to have diabetes than Aryans, as evidence of their genetic unfitness, but this was more about being anti-Semitic than anti-diabetes).