Occult hypoglycemia caused by hemodialysis.

Background: Previous studies have ignored hypoglycemia in patients undergoing hemodialysis. The fall in plasma glucose may not have been considered to be clinically relevant because the patients were asymptomatic. The present study was designed to assess the effect of hemodialysis on plasma glucose, insulin, glucagon, cortisol and catecholamines in non diabetic patients.

Methods: 21 non diabetic patients with chronic renal failure were hemodialyzed using a glucose-free dialysis fluid. They did not take any medication prior to dialysis and were asked not to eat during the first hour on hemodialysis. Blood and dialysate fluid was sampled at regular intervals during the first hour of dialysis for analysis.

Results: Plasma glucose fell below 4.0 mmol/l (72 mg/dl) in 9 of the 21 patients, below 3.5 mmol/l (63 mg/dl) in 6 and below 3.0 mmol/l (54 mg/dl) in 3. The lowest recorded value was 2.1 mmol/l (38 mg/dl). The mode glucose loss in the waste dialysate fluid was 6 g/h. In the group of 9 patients whose plasma glucose fell below 4.0 mmol/l (72 mg/dl), no symptoms of hypoglycemia were shown but 4 of the 7 patients who felt very hungry and ate were in this group. When 7 patients from this group were subsequently dialysed with a dialysis fluid containing 5.5 mmol/l (100 mg/dl) glucose, their plasma glucose became stabilized within the fasting reference range. There were no significant hormonal changes during the dialysis or between euglycemic and hypoglycemic patients.

Conclusions: Patients undergoing hemodialysis may become hypoglycemic and not be aware of it. There is no hormonal imbalance causing the hypoglycemia and the hormonal response to the hypoglycemia is blunted. Patients with an initial plasma glucose of 4.5 mmol/l (81 mg/dl) or less who are hemodialyzed and who do not eat during dialysis may be particularly at risk. They should be dialysed with a dialysis fluid containing at least 5.5 mmol/l (100 mg/dl) glucose.