More than one in five people with type 1 diabetes also have another autoimmune condition, according to findings from a large study of adults in Finland.

Almost 4800 patients from a Finnish registry of people with type 1 diabetes (mean age 51, mean 36 years diabetes duration) were matched with 12,700 controls from the general population who did not have the disease.

Some 23% of the people with diabetes — 32% of women and 15% of men — had at least one other autoimmune disease, including hypothyroidism or hyperthyroidism, coeliac disease, atrophic gastritis or Addison’s disease.

Nearly 20% had one additional autoimmune disease, 3% had two extra autoimmune diseases, 0.13% had three, and one patient had four more.