An emergency intervention was performed in a 75-year-old male patient with hypoglycemic attack and blackout. Although he was diagnosed with prediabetes before 2 years, he did not take any anti-diabetic drug or follow dietary advice. He drank Vaccinium corymbosum L (VC) juice daily with a belief that it increases sexual potency. Before the development of hypoglycemia, the patient had consumed about 500 ml VC juice in addition to eating 200-300 gram of Laurocerasus officinalis (LO) fruit. The measured plasma glucose (PG) level during loss of consciousness was 30 mg/dl. The profound hypoglycemia may be an unexpected side effect of an interaction between the chemical compositions of the two plants, occurred as a result of LO fruit intake that may have a strong PG-lowering effect or related to excessive intake of VC juice. Both plants may be considered in the alternative treatment of diabetes.