Integrated longitudinal metabolic monitoring before, during and after teplizumab in an adult with stage 2 type 1 diabetes: a case report

Background Teplizumab is the first disease-modifying therapy approved to delay progression from stage 2 to stage 3 type 1 diabetes (T1D). Although its efficacy has been demonstrated in randomized clinical trials, the optimal strategy for monitoring the early metabolic response after treatment has not yet been established. Case presentation We report the case of a 19-year-old woman diagnosed with stage 2 T1D after severe corticosteroid-associated hyperglycemia unmasked an underlying autoimmune dysglycemic state. The diagnosis was confirmed by progressive deterioration in serial oral glucose tolerance test (OGTT), positivity for multiple islet autoantibodies and preserved endogenous insulin secretion. Following a standard 14-day course of intravenous teplizumab, the patient underwent prospective metabolic evaluation using serial OGTT, mixed-meal tolerance testing (MMTT), continuous glucose monitoring (CGM), pancreatic autoantibodies, screening for extra-pancreatic autoimmunity and safety assessments. Twelve weeks after treatment, OGTT normalized and stimulated C-peptide secretion remained preserved during MMTT, while CGM provided longitudinal characterization of ambulatory glucose profiles throughout the 24-week follow-up, without evidence of progression to stage 3 T1D. Conclusions This case illustrates how OGTT, MMTT and CGM can provide complementary information on glucose tolerance, endogenous β-cell function and real-world glycemic homeostasis during early follow-up after teplizumab. Although no conclusions regarding optimal monitoring strategies can be drawn from a single patient, this longitudinal characterization may help inform the design of prospective studies evaluating metabolic monitoring after disease-modifying therapy in stage 2 T1D.