Relationship between islet autoantibody status and the clinical characteristics of children and adults with incident type 1 diabetes in a UK cohort

Objectives To describe the characteristics of children and adults with incident type 1 diabetes in contemporary, multiethnic UK, focusing on differences between the islet autoantibody negative and positive. Design Observational cohort study. Setting 146 mainly secondary care centres across England and Wales. Participants 3312 people aged >= 5 years were recruited within 6 months of a clinical diagnosis of type 1 diabetes via the National Institute for Health Research Clinical Research Network. 3021 were of white European ethnicity and 291 (9%) were non-white. There was a small male predominance (57%). Young people <17 years comprised 59%. Main outcome measures Autoantibody status and characteristics at presentation. Results The majority presented with classical osmotic symptoms, weight loss and fatigue. Ketoacidosis was common (42%), especially in adults, and irrespective of ethnicity. 35% were overweight or obese. Of the 1778 participants who donated a blood sample, 85% were positive for one or more autoantibodies against glutamate decarboxylase, islet antigen-2 and zinc transporter 8. Presenting symptoms were similar in the autoantibody-positive and autoantibody-negative participants, as was the frequency of ketoacidosis (43% vs40%, P=0.3). Autoantibody positivity was less common with increasing age (P=0.0001), in males compared with females (82% vs90%, P<0.0001) and in people of non-white compared with white ethnicity (73% vs86%, P<0.0001). Body mass index was higher in autoantibody-negative adults than autoantibody-positive adults (median, IQR 25.5, 23.1-29.2vs23.9, 21.4-26.7 kg/m(2); P=0.0001). Autoantibody-negative participants were more likely to have a parent with diabetes (28% vs16%, P<0.0001) and less likely to have another autoimmune disease (4% vs8%, P=0.01). Conclusions Most people assigned a diagnosis of type 1 diabetes presented with classical clinical features and islet autoantibodies. Although indistinguishable at an individual level, autoantibody-negative participants as a group demonstrated features more typically associated with other diabetes subtypes.