SummaryBackgroundLight at night disrupts circadian rhythms, and circadian disruption is a risk factor for type 2 diabetes. Whether personal light exposure predicts diabetes risk has not been demonstrated in a large prospective cohort. We therefore assessed whether personal light exposure patterns predicted risk of incident type 2 diabetes in UK Biobank participants, using ∼13 million hours of light sensor data.MethodsParticipants (N = 84,790, age (M ± SD) = 62.3 ± 7.9 years, 58% female) wore lig...