would have fainting spells; anytime she would eat her blood sugar would go up to 250-260; 20-30min later would go down to 40-60; caused her to loose a lot of weight; she could not eat/ she is not able to eat any carbs or rice, Indian bread or any sugar.; headache; tightness of neck; 1st 05Apr2021, 2nd 26Apr2021 and 3rd 26Aug2021; This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP) from medical information team.  A 54 year-old female patient received bnt162b2 (BNT162B2), administration date 26Aug2021 (Batch/Lot number: unknown) as dose 3 (booster), single for covid-19 immunisation. The patient's relevant medical history and concomitant medications were not reported. Vaccination history included: Covid-19 vaccine (Dose: 2, Primary Immunization series complete but unknown manufacturer), administration date: 26Apr2021, for Covid-19 immunization; Covid-19 vaccine (Dose: 1, Primary Immunization series complete but unknown manufacturer), administration date: 05Apr2021, for COVID-19 immunization. The following information was reported: SYNCOPE (medically significant), outcome "unknown", described as "would have fainting spells"; HYPERGLYCAEMIA (medically significant), outcome "unknown", described as "anytime she would eat her blood sugar would go up to 250-260"; HYPOGLYCAEMIA (medically significant), outcome "unknown", described as "20-30min later would go down to 40-60"; WEIGHT DECREASED (medically significant), outcome "unknown", described as "caused her to loose a lot of weight"; EATING DISORDER (non-serious), outcome "not recovered", described as "she could not eat/ she is not able to eat any carbs or rice, Indian bread or any sugar."; HEADACHE (non-serious), outcome "unknown", described as "headache"; MUSCLE TIGHTNESS (non-serious), outcome "unknown", described as "tightness of neck"; INAPPROPRIATE SCHEDULE OF PRODUCT ADMINISTRATION (non-serious), outcome "unknown", described as "1st 05Apr2021, 2nd 26Apr2021 and 3rd 26Aug2021". The events "would have fainting spells", "anytime she would eat her blood sugar would go up to 250-260" and "20-30min later would go down to 40-60" were evaluated at the emergency room visit. The patient underwent the following laboratory tests and procedures: allergy test: unknown result; blood glucose fluctuation: 250-260; 40-60; endoscopy: unknown result; weight: loose a lot of weight.  Clinical course: As per caller his wife received 3 doses of the vaccine: 1st 05Apr2021, 2nd 26Apr2021 and 3rd 26Aug2021. "After the first and second dose, she had fatigue, headache, anxiety issues. After the 3rd dose (1-2 weeks later) she could not eat, headache, tightness of neck, anytime she would eat her blood sugar would go up to 250-260 and 20-30min later would go down to 40-60 and would had fainting spells. My 16 year old son was with her at the time an they had to take her to the Emergency Room a couple of times. She was still having this issue, she was not able to eat any carbs or rice, Indian bread or any sugar.She can only had oatmeal and this had caused her to loose a lot of weight because everything leads to sugar highs and lows. She didn't had this before, she had no family history of diabetes. Yesterday we were read information online and people are pointing towards sugar issues related to the vaccine, some people became diabetic, or hypoglycemia issues, some are on insulin. They were still doing tests, she will had a stomach imaging tomorrow, they did an endoscopy and did allergy test we had seen many doctors. My wife never took diabetes meds before. Did you had any other reports of this issue with the sugar i.e. affecting liver or pancreas"?   The lot number for bnt162b2 was not provided and will be requested during follow up.