This is a literature report for the following literature source(s): "COVID-19 Vaccine Related Hyperosmolar Hyperglycemic State and Normalized Glycemia within 2 Months", 2022; Vol:12, pgs:12-17, DOI:10.4236/jdm.2022.121002. A 56 year-old male patient received bnt162b2 (BNT162B2) (Batch/Lot number: unknown) as dose 2, single for Covid-19 immunisation. Relevant medical history included: "hypertension" (unspecified if ongoing); "primary hyperparathyroidism" (unspecified if ongoing); "goiter" (unspecified if ongoing); "primary hypothyroidism" (unspecified if ongoing), notes: on levothyroxine; "obesity" (unspecified if ongoing); "hyperlipidemia" (unspecified if ongoing); "former smoker" (unspecified if ongoing), notes: 37 pack years; quit smoking; "alcohol use" (unspecified if ongoing), notes: two years prior to hospitalization, never a heavy alcohol user. Concomitant medication(s) included: LEVOTHYROXINE taken for primary hypothyroidism; ATORVASTATIN taken for hypertension. Vaccination history included: Covid-19 vaccine (DOSE 1, SINGLE (MANUFACTURER UNKNOWN)), for COVID-19 immunization. The following information was reported: HYPERGLYCAEMIC HYPEROSMOLAR NONKETOTIC SYNDROME (hospitalization, medically significant), outcome "recovered", described as "Hyperosmolar Hyperglycemic State". The patient was hospitalized on an unspecified date. The patient underwent the following laboratory tests and procedures: blood chloride: (03May2021) 82; (04May2021) 103; (18Jun2021) 109; blood creatinine: (unspecified date) 2.7, notes: acute renal insufficiency with creatinine 2.7; (unspecified date) normalized, notes: normalized after IV fluids and treatment with insulin; (03May2021) 2.7; (04May2021) 1.3; (18Jun2021) 1.1; blood glucose: (unspecified date) more than 900, notes: Blood glucose fluctuation; (unspecified date) improved; (03May2021) 997; (04May2021) 136; (18Jun2021) 158; blood potassium: (03May2021) 6.1; (04May2021) 3.1; (18Jun2021) 4.4; blood sodium: (03May2021) 118; (04May2021) 139; (18Jun2021) 139; blood urea: (03May2021) 38; (04May2021) 18; (18Jun2021) 19; body mass index: (unspecified date) 33.5; carbon dioxide: (03May2021) 13; (04May2021) 30; (18Jun2021) 19; full blood count: (unspecified date) rapid changes at hospitalization; (unspecified date) improved rapidly, notes: Improved rapidly after discharge without any intervention; glomerular filtration rate: (unspecified date) normalized, notes: normalized after IV fluids and treatment with insulin; (03May2021) 30; (04May2021) greater than 60; (18Jun2021) greater than 60; glycosylated haemoglobin: (unspecified date) came down to 4.9, notes: by 40 days after discharge; (unspecified date) 5.6, notes: forty-five days prior to presentation with HbA1C of greater than 14 and hyperosmolarity state; haematocrit: (03May2021) 41.7; (05May2021) 30.6; (14May2021) 17.5; (15Jul2021) 337.4; haemoglobin: (03May2021) 13.3; (05May2021) 9.9; (14May2021) 5.6; (15Jul2021) 12.5; mean cell volume: (03May2021) 95.9; (05May2021) 92.3; (14May2021) 100.9; (15Jul2021) 92.4; physical examination: (unspecified date) revealed obese male; (unspecified date) thyromegaly and oral thrush, notes: Had thyromegaly and oral thrush. No other abnormalities on physical exam; platelet count: (03May2021) 196; (05May2021) 141; (14May2021) 335; (15Jul2021) 243; white blood cell count: (03May2021) 16.4; (05May2021) 11.7; (14May2021) 14.7; (15Jul2021) 11.7. Therapeutic measures were taken as a result of hyperglycaemic hyperosmolar nonketotic syndrome. Clinical course: A 56-year-old obese Afro-American male with a past medical history of hypertension, primary hyperparathyroidism, goiter and primary hypothyroidism on levothyroxine, obesity and hyperlipidemia was hospitalized to medical intensive care unit with hyperosmolar hyperglycemic state with blood sugar more than 900 and acute renal insufficiency with creatinine of 2.7. His symptoms of polyurea and increased thirst following second dose of Pfizer-BioNTech COVID-19 vaccine. Thirst was so severe, drank three gallons of juice and water, couple of days prior to hospitalization. He felt confused and spilled gasoline on his clothes and became unsteady on the day of hospitalization. In addition, he had throat pain and mild cough, decreased visual acuity (blurring). Personal history significant for former smoker of 37 pack years. Quit smoking and alcohol use two years prior to hospitalization. Never heavy alcohol user. No family history of diabetes. His at home meds included anti-hypertensives, atorvastatin and levothyroxine 125 mcg a day. Physical exam revealed obese male with BMI of 33.5, cooperative and not in distress, appeared to be appropriate for stated age, well-built and nourished male. Had thyromegaly and oral thrush. No other abnormalities on physical exam. He was hospitalized and appropriately treated in ICU with large doses of intravenous fluids, intra venous insulin drip of moderate doses and other supportive care. Later the insulin doses were transitioned to basal bolus insulins. Relevant diabetes related labs with changes over time. Blurring and visual acuity improved as sugars improved. Creatinine and eGFR normalized after IV fluids and treatment with insulin. Oral thrush was treated with oral nystatin suspension. Follow up: Post discharge, he received gradual tapering doses of insulin and later insulin was discontinued and recovered to normal glycemic state off anti-diabetic meds. His HbA1C came down to 4.9 by 40 days after discharge. Rapid changes in blood counts at hospitalization also improved rapidly after discharge without any intervention. His glycemic state remained normal five months after discharge. Interesting features: 1) Development of hyperosmolarity starting after the second dose of the vaccine in a patient with no family history of diabetes and HbA1C of 5.6, forty-five days prior to presentation with HbA1C of greater than 14 and hyperosmolarity state. 2) Rapid rise and rapid recovery of glycemic state. 3) Rapid drop in blood counts and rapid recovery. Conclusion: The patient presented with a hyperosmolar state and his symptoms started right after the second dose after receiving the BNT162b2 vaccine and had no other risk factors for the condition. Hence it was considered that the acute hyperglycemic state was the effect of the BNT162b2 vaccine. In addition, he recovered his pancreatic function to a prediabetic state within less than 2 months. This publication is for the clinicians to be aware of possible side effects of the vaccine as consideration and need for close follow-up care to avoid hypoglycemia as they recover. In addition to glycemic changes, he had changes in hemoglobin and hematocrit, with recovery in 3 months, probable effect on bone marrow. No follow-up attempts are possible; information about lot/batch number cannot be obtained. No further information is expected. Sender's Comments: Based on possible temporal association the causal role of BNT162B2 Vaccine cannot be excluded for reported events. Case will be reviewed further on receipt of FU information. The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to regulatory authorities, Ethics Committees, and Investigators, as appropriate.