Glucose Control in Severely Burned Patients Using Metformin

OBJECTIVE: To determine whether metformin can achieve glucose control no worse than insulin (noninferiority) without the danger of hypoglycemia (superiority). In addition, to assess whether metformin has any additional effects on lipolysis and inflammation that will enhance burn recovery (superiority). SUMMARY BACKGROUND DATA: Hyperglycemia and insulin resistance after burn injury are associated with increased morbidity and mortality. Insulin administration improves postburn infections, severity of sepsis, and morbidity, but also causes a 4-5-fold increase in hypoglycemia, which is associated with a 9-fold increase in mortality. METHODS: Severely burned adult patients with burns over 20% total body surface area (TBSA) burn were prospectively randomized in this Phase II clinical trial to either metformin or insulin (standard of care) treatment. Primary outcomes were glucose levels and incidence of hypoglycemia. Secondary outcomes included glucose and fat metabolism, and clinical outcomes. RESULTS: Forty-four patients were enrolled in this Phase II clinical trial, 18 metformin and 26 insulin patients. Demographics, burn size, concomitant injuries, and mortality were comparable between both groups. Metformin controlled blood glucose as equally as insulin with no difference between the 2 treatment groups, P > 0.05. While there was a 15% incidence of hypoglycemia in the insulin group, there was only 1 mild hypoglycemic episode (6%) in the metformin group, P < 0.05. Oral glucose tolerance tests at discharge revealed that metformin significantly improved insulin sensitivity, P < 0.05. Furthermore, metformin had a strong antilipolytic effect after burn injury when compared with insulin and was associated with significantly reduced inflammation, P < 0.05. CONCLUSIONS: Metformin decreases glucose equally as effective as insulin without causing hypoglycemia, with additional benefits including improved insulin resistance and decreased endogenous insulin synthesis when compared with insulin controls. These results indicate that metformin is safe in burn patients and further supports the use of metformin in severely burned patients for postburn control of hyperglycemia and insulin resistance.