Hypoglycemia; This spontaneous case was reported by a consumer and describes the occurrence of HYPOGLYCAEMIA (Hypoglycemia) in a 67-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.     Concurrent medical conditions included Metastatic carcinoid tumor (ongoing) since 01-Jun-2012, Type II diabetes mellitus (ongoing) since 27-Mar-2019 and Carcinoid tumor. Concomitant products included PEMBROLIZUMAB from 27-Aug-2021 to an unknown date for Carcinoid tumor, INSULIN LISPRO (HUMALOG) from 19-Nov-2021 to 29-Nov-2021, INSULIN ASPART (NOVOLOG) from 29-Nov-2021 to an unknown date and METFORMIN from 27-Mar-2019 to 22-Nov-2021 for Type 2 diabetes mellitus.    On 29-Oct-2021, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 29-Nov-2021, the patient experienced HYPOGLYCAEMIA (Hypoglycemia) (seriousness criterion hospitalization). The patient was hospitalized from 29-Nov-2021 to 04-Dec-2021 due to HYPOGLYCAEMIA. On 04-Dec-2021, HYPOGLYCAEMIA (Hypoglycemia) had resolved. Not Provided    DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 29-Nov-2021, Blood glucose (70-130 mg/dl): 50 mg/dl (Low) 50mg/dL. On 30-Nov-2021, Blood glucose (70-130 mg/dl): 170 mg/dl (High) 170mg/dL. On 01-Dec-2021, Blood glucose (70-130 mg/dl): 210 mg/dl (High) 210mg/dL. On 02-Dec-2021, Blood glucose (70-130 mg/dl): 41 mg/dl (Low) 41mg/dL. On 03-Dec-2021, Blood glucose (70-130 mg/dl): 130 mg/dl (normal) 130mg/dL. On 04-Dec-2021, Blood glucose (70-130 mg/dl): 120 mg/dl (normal) 120mg/dL.     mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown) dosing remained unchanged.       No Treatment medications were reported.  The Birth date of patient was Sep-1954. The participant has a history of type 2 diabetes that was initially well-controlled on Metformin. However, since beginning treatment on the immune checkpoint inhibitor pembrolizumab (start date 8/27/2021), his blood sugar levels had been unstable. Per the discharge summary, he was admitted on 11/29/2021 with hypoglycemia and labile blood sugars for the purpose of blood sugar stabilization and regime. Blood glucoses at admission ranged from 51 to 300mg/dL. He was discharged on 12/4/2021 once his blood sugar stabilized with instruction to discontinue long-acting insulin and to proceed with a low-dose sliding scale coverage.  Company comment: This regulatory case concerns a 67-year-old male patient with history of type 2 diabetes in treatment with metformin and insulin and metastatic small bowel carcinoid tumor in treatment with pembrolizumab, who experienced the unexpected, serious (hospitalization) event of HYPOGLYCAEMIA. The event occurred approximately 1 month after receiving a third dose of mRNA-1273. The rechallenge is not applicable since further dosing is not expected. Patient was admitted for 4 days to the hospital, and even if he was admitted with hypoglycaemia of 50 mg/dL, his blood glucose levels were unstable during hospitalization, going from 41mg/dL to 300mg/dL. Reporter considered that this event was not related to mRNA-1273 since patient has experienced unstable blood glucose levels since he started treatment with pembrolizumab about 2 months prior to the third dose of mRNA-1273. Patient's history of diabetes also remains as a confounder. The benefit-risk relationship of mRNA-1273 is not affected by this report.; Sender's Comments: This regulatory case concerns a 67-year-old male patient with history of type 2 diabetes in treatment with metformin and insulin and metastatic small bowel carcinoid tumor in treatment with pembrolizumab, who experienced the unexpected, serious (hospitalization) event of HYPOGLYCAEMIA. The event occurred approximately 1 month after receiving a third dose of mRNA-1273. The rechallenge is not applicable since further dosing is not expected. Patient was admitted for 4 days to the hospital, and even if he was admitted with hypoglycaemia of 50 mg/dL, his blood glucose levels were unstable during hospitalization, going from 41mg/dL to 300mg/dL. Reporter considered that this event was not related to mRNA-1273 since patient has experienced unstable blood glucose levels since he started treatment with pembrolizumab about 2 months prior to the third dose of mRNA-1273. Patient's history of diabetes also remains as a confounder. The benefit-risk relationship of mRNA-1273 is not affected by this report.