Immune checkpoint inhibitor-induced type 1 diabetes (ICI-T1D) is a rare immune-related adverse event (irAE) of immune checkpoint inhibitors (ICIs). This retrospective study aimed to characterize the clinical features and glucose patterns of ICI-T1D in Chinese individuals and compare them with those of traditional T1D. Between January 2019 and April 2024, 15 patients diagnosed with ICI-T1D were consecutively enrolled. Continuous glucose monitoring (CGM) data from 7 of these patients were compared with data from 14 traditional T1D patients, matched for age, sex, fasting C-peptide levels, and diabetes duration. Median time from ICI initiation to T1D onset was 16 weeks (IQR, 6-96). Notably, T1D developed in four participants at 144, 112, 108, and 96 weeks after PD-1 treatment, respectively. Three ICI-T1D had pre-existing type 2 diabetes (T2D). Moreover, two had concurrent hypothyroidism and adrenal insufficiency alongside ICI-T1D. CGM analysis suggested that ICI-T1D exhibited a higher overall coefficient of variation (CV) (36.3 ± 4.8% vs. 28.2 ± 6.5%
p = 0.009), a greater CV during the night (37.4 ± 8.4% vs. 23.4 ± 7.3%
p = 0.001), and an increased standard deviation (SD) during the night (3.3 ± 0.8 mmol/L vs. 2.1 ± 1.1 mmol/L
p = 0.017) compared to those with traditional T1D. The study highlighted diverse clinical presentations of ICI-T1D, including delayed onset and multiple endocrine organs dysfunctions after ICI treatment. Consequently, long-term glucose monitoring and early identification are crucial. Furthermore, the observed greater glucose variability in ICI-T1D emphasizes the critical importance of diabetes education and personalized insulin regimen.