An Impaired Awareness of Hypoglycemia Improved After Vitamin B₁₂ Treatment in a Type 1 Diabetic Patient

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An impaired awareness of hypoglycemia is a serious problem in diabetic patients, which can lead to life-threatening severe hypoglycemia. Recurrent hypoglycemia attenuates the function of the central, mainly hypothalamic, nervous system and it causes an impaired awareness of hypoglycemia. Vitamin B₁₂ deficiency is also associated with the dysfunction of central nervous system. We report a 72-year-old type 1 diabetic patient with vitamin B₁₂ deficiency whose impaired awareness of hypoglycemia improved after 4 weeks of vitamin B₁₂ administration with an increased counter-hormone secretion in response to hypoglycemia. We should recognize vitamin B₁₂ deficiency as one of the causes of an impaired awareness of hypoglycemia in diabetic patients.