HYPERGLYCAEMIA DEFINITION Hyperglycaemia is defined as a blood glucose concentration greater than 115 mg/dL (6.3 mmol/L), although a level of 150 mg/dL (8.3 mmol/L) is more commonly recognized as abnormal. TOXIC CAUSES Alloxan Amphetamines Beta-2-adrenergic agents Beta-1-adrenergic blocking drugs Caffeine Calcium channel blockers Cocaine and amphetamines Corticosteroids Dextrose Diazoxide Epinephrine (Adrenaline) Glucagon Iron Pentamidine Somatotrophin (Human Growth Hormone) Streptozocin Theophylline Vacor (PNU) NON-TOXIC CAUSES Diabetes mellitus Other endocrine disorders Seizures Stress with sympathetic system activation CLINICAL FEATURES Moderate hyperglycaemia causes no symptoms. At higher blood glucose concentrations, glucosuria leads to osmotic diuresis and dehydration. Very high concentrations (greater than 600 to 800 mg/dL [33 to 44 mmol/L]) can cause obtundation or coma as a result of serum hyperosmolality. Patients with drug-induced hyperglycaemia usually have other manifestations of the intoxication which help suggest the diagnosis. For example, overdose of salbutamol (albuterol) or other beta-adrenergic agents causes tachycardia, widened pulse pressure, agitation, and hypokalaemia. Similar findings may be seen with intoxication by caffeine or theophylline, both of which are also associated with seizures at high levels. Calcium antagonists such as verapamil cause hyperglycaemia accompanied by hypotension and cardiac conduction defects. Iron poisoning causes vomiting and diarrhea, and radiopaque iron tablets are often visible on abdominal radiographs. DIFFERENTIAL DIAGNOSIS Other causes of coma and dehydration including: Hypernatraemia (eg, diabetes insipidus) Hypercalcaemia Hypovolaemia from vomiting, dehydration, etc. Ingestion of alcohols RELEVANT INVESTIGATIONS Rapid blood glucose measurement. This may be performed by the hospital laboratory or at the bedside using fingerstick capillary blood and a portable battery-operated analyzer or a test strip. The presence of glucose on dipstick testing of the urine suggests an elevated blood glucose concentration. Serum electrolytes Serum ketones Renal function tests (urea, creatinine) TREATMENT In general, drug-induced hyperglycaemia does not require treatment, and efforts can be focused on other manifestations of the specific overdose, such as treatment of shock or seizures. For patients with evidence of dehydration, administer intravenous fluids (preferably normal saline). For significantly elevated blood sugar concentrations, consider intravenous insulin. CLINICAL COURSE AND MONITORING Serum glucose levels should be monitored only if they are very high (greater than 19 to 22 mmol/L [350 to 400 mg/dL]). Decisions about hospital admission and length of emergency monitoring will depend largely on the specific overdose. POTENTIAL COMPLICATIONS Not common. Permanent insulin-dependent diabetes mellitus may occur after poisoning by Vacor, pentamidine, alloxan or streptozocin. AUTHORS AND REVIEWERS Author: Dr K R Olson, University of California, San Francisco. Peer review: Cardiff 9/96: V. Afanasiev, M. Burger, T. Della Puppa, L. Fruchtengarten, K. Olsen, J. Szajewski.