A Case of Type 2 Diabetes Mellitus Complicated by Recurrent Hypokalemic Myopathy in a Patient with a Long-term History of Heavy Soft Drink Consumption

Abstract

A 39-year-old female was emergently admitted to the hospital with thirst, vomiting and weakness in the extremities. She had a 10-year history of consumption of 3-4.5 l/day of cola. Her blood glucose level was 638 mg/dl, her HbA1c level was 14.3 %and her urine tested positive for ketone bodies; therefore, she was diagnosed with diabetic ketoacidosis. The results of an arterial blood gas analysis were within the normal range, at a pH of 7.42. The serum anion gap was 16, indicating metabolic acidosis. The serum HCO₃^-level was 30 mmol/l, which suggested concomitant metabolic alkalosis. Marked hypokalemia (1.9 mEq/l) was also noted. Nevertheless, no hypertension was observed, and the results of hormone assays excluded the possibility of endocrine disease. Therefore, the caffeine in the cola was a suspected cause of the patient's hypokalemia, and a caffeine tolerance test was performed. Since a reduction in the blood potassium level (from 4.0 mEq/l to 2.4 mEq/l) was observed with a slight decrease in the urinary potassium level, an intracellular potassium shift was considered to have caused the hypokalemia. When soft drink ketosis complicated by marked hypokalemia is observed in patients with diabetes, the excessive intake of caffeine-containing beverages should be suspected as a possible etiology.