Executive Dysfunction After COVID-19 in an Older Adult With Type 1 Diabetes: A Case of Insulin Pump Discontinuation

Continuous subcutaneous insulin infusion (CSII) and multiple daily injections (MDIs) are the two main approaches to intensive insulin therapy. CSII provides flexible basal-bolus adjustments and can improve glycemic variability, but it requires preserved executive function for tasks such as infusion set replacements, bolus programming, and troubleshooting in response to pump alarms. In contrast, MDI involves more injections but is simpler to operate and less cognitively demanding. Advanced diabetes technologies such as CSII require more than intact cognition; they rely on real-world executive function and consistent self-management, especially in older adults with type 1 diabetes mellitus (T1DM). Even common infections, such as COVID-19, can unmask functional vulnerabilities that compromise the safety of such therapies. Post-infectious changes in attention, decision-making, or nutrition may precede detectable impairments on tools like the Montreal Cognitive Assessment (MoCA). Here, we describe the case of a 73-year-old woman with a 28-year history of T1DM who had been independently and stably using CSII. Following a COVID-19 infection, she developed fatigue, dysgeusia, and appetite loss. Despite a high MoCA-J score (29/30), she experienced recurrent episodes of diabetic ketoacidosis (DKA). Direct pump log review was not possible. Missed mealtime boluses were inferred from preadmission self-monitoring of blood glucose patterns showing frequent missing entries and, when available, marked postprandial hyperglycemia, together with the patient's inconsistent recollection of bolus administration. Although these indirect findings could not definitively prove pump errors, they suggested impaired executive function. Laboratory testing showed zinc deficiency (63 µg/dL), and supplementation improved taste and oral intake. Due to persistent pump-related errors and reduced confidence, her insulin regimen was transitioned to MDIs, resulting in stable glycemic control without further DKA, although she required one additional hospitalization for post-COVID-19 anorexia and nutritional decline over a three-month follow-up period. In older adults with T1DM, even seemingly mild illnesses such as COVID-19 can trigger disproportionate functional decline. Clinicians should recognize that executive dysfunction may precede cognitive test abnormalities. Incorporating functional assessments and simplifying therapy when indicated may help prevent severe outcomes such as DKA in this vulnerable population.