INS and thyrotoxicosis: Throughout her 12-day admission, she maintained normal vital signs with no clinical evidence of sympathetic overactivity despite prolonged biochemical thyrotoxicosis.<h4>Conclusions</h4>Co-ingestion of insulin and levothyroxine appears to minimize symptomatic thyrotoxicosis risk, potentially through inhibition of thyroxine to triiodothyronine conversion and glucose homeostasis maintenance.