had a very severe adverse effect to the booster vaccine that caused a major horrific automobile incident; from fully functional to very disoriented; had a severe low blood sugar/ experienced high sugar, body wasn't reacting to the insulin/ goes from a very high reading to a very low reading (300 to 45) in seconds to minutes; This spontaneous case was reported by a patient and describes the occurrence of BLOOD GLUCOSE FLUCTUATION (had a severe low blood sugar/ experienced high sugar, body wasn't reacting to the insulin/ goes from a very high reading to a very low reading (300 to 45) in seconds to minutes), ROAD TRAFFIC ACCIDENT (had a very severe adverse effect to the booster vaccine that caused a major horrific automobile incident) and DISORIENTATION (from fully functional to very disoriented) in a 67-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. ASKU) for COVID-19 prophylaxis.     Concurrent medical conditions included Type I diabetes mellitus. Concomitant products included INSULIN for Type 1 diabetes mellitus.    On 13-Feb-2022, the patient received dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 17-Dec-2022,  after starting mRNA-1273 (Moderna COVID-19 Vaccine), the patient experienced BLOOD GLUCOSE FLUCTUATION (had a severe low blood sugar/ experienced high sugar, body wasn't reacting to the insulin/ goes from a very high reading to a very low reading (300 to 45) in seconds to minutes). On 21-Dec-2022, the patient experienced ROAD TRAFFIC ACCIDENT (had a very severe adverse effect to the booster vaccine that caused a major horrific automobile incident) and DISORIENTATION (from fully functional to very disoriented). At the time of the report, BLOOD GLUCOSE FLUCTUATION (had a severe low blood sugar/ experienced high sugar, body wasn't reacting to the insulin/ goes from a very high reading to a very low reading (300 to 45) in seconds to minutes), ROAD TRAFFIC ACCIDENT (had a very severe adverse effect to the booster vaccine that caused a major horrific automobile incident) and DISORIENTATION (from fully functional to very disoriented) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In 2022, Blood glucose: Sometimes it goes from 300 to 45 unbeknownst to the patient and it goes from a very high reading to a very low reading in seconds to minutes and had the data from patient's sugar readings. There were notable tragic differences that patient experienced.. On 17-Dec-2022, Blood glucose: low blood sugar. On 21-Dec-2022, Blood glucose: high sugar readings.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered BLOOD GLUCOSE FLUCTUATION (had a severe low blood sugar/ experienced high sugar, body wasn't reacting to the insulin/ goes from a very high reading to a very low reading (300 to 45) in seconds to minutes) and ROAD TRAFFIC ACCIDENT (had a very severe adverse effect to the booster vaccine that caused a major horrific automobile incident) to be related. No further causality assessment was provided for DISORIENTATION (from fully functional to very disoriented).    Patient didn't received any other vaccine 4 weeks prior to COVID-19 vaccine.  Patient didn't had the vaccination card because it was on the accident. On 17-Dec-2022, patient had an event at the place of employment called paramedics that patient had a severe low blood sugar. Things were bottoming out and higher than normal and was gave a candy bar. Patient totaled car on 21-Dec-2022.  Patient body wasn't reacting to the insulin that patient was taking and was not able to bring the sugars down. It was very problematic and  life changing.  Treatment medication was not provided.