BACKGROUND Hypoglycemia can cause a diffuse brain malfunction and sometimes a focal neurological deficiency, that could lead to a mistaken diagnosis of cerebrovascular disease. METHODS We describe the case of a 67 year old man, with diabetes mellitus type II treated with glibenclamide, that was referred to our hospital due to worsening of his chronic obstructive pulmonary disease. On the fifth day following admission he developed acute weakness in the right extremities and experienced difficulty in talking: six hours later he was conscious, with normal eye movements, but there was an absence of spontaneous facial motility and to pain; he showed complete cuadraplegia and bilateral Babinski. A determination of glycemia was made with the result of 24 mg/dl; after immediate treatment with glucose solution intravenously the patient recovered in a few minutes. CONCLUSIONS This clinical observation reminds us of the importance of determining blood glucose in the assessment of any acute neurological dysfunction.