eng Science and Education Publishing American Journal of Medical Case Reports 2374-216X 2023-02-23 11 2 37 40 10.12691/ajmcr-11-2-8 AJMCR20231128 article Ken-ichi Muramatsu 1 Ikuto Takeuchi 1 Soichiro Ota 1 Youichi Yanagawa yyanaga@juntendo.ac.jp 1 Department of Acute Critical Care Medicine, Juntendo Shizuoka Hospital, Izunokuni, Japan A 52-year-old male was transported to a local medical facility due to unconsciousness and involuntary movement. His past history included only hypertension. He consumed over 2 L of soft drink per day. His body mass index was 34. As he had hyperosmolar hyperglycemic syndrome and COVID-19 infection, he was transferred to our department. On arrival, he was in a coma and pre-shock state. He was therefore intubated. Initially, his blood C-peptide level was low, and he showed hyperglycemia with ketosis. Whole body computed tomography (CT) showed pneumonia. He was diagnosed with hyperosmolar hyperglycemic syndrome with ketosis, COVID-19 infection, convulsion, hemoconcentration, liver dysfunction, rhabdomyolysis, pancreatitis, renal failure and hypernatremia. He was admitted to the intensive care unit, where he was successfully treated. His blood C-peptide returned to the normal range (2.2 ng/mL) on day 20, and he returned to the local medical facility on day 21. This is the first report of transient decrease in insulin secretion after COVID-19 infection in a patient with a combination hyperosmolar hyperglycemic syndrome and ketosis. Further prospective studies are needed to clarify the characteristics of the insulin secretion function following COVID-19 infection. http://pubs.sciepub.com/ajmcr/11/2/8/ajmcr-11-2-8.pdf COVID-19 soft drink hyperglycemic hyperosmolar syndrome c-peptide