For patients who suffer from severe chronic pancreatitis, total pancreatectomy can alleviate pain, and islet autotransplantation (IAT) might preserve endocrine function and circumvent the complications of diabetes. Factors that determine success after this operation have not been clearly defined. From 2000 to 2004, 45 total or subtotal pancreatectomies with IAT were performed. Patient characteristics, narcotic usage and insulin requirements were recorded at routine followup. Narcotic usage was standardized by conversion to morphine equivalents (MEs). Univariate and multivariate statistical analyses were performed to determine factors associated with insulin and narcotic independence. Forty-five patients (30 women, 15 men), with a mean age of 39 years (range 16 to 62 years) underwent total or completion (n=41) or subtotal (n=4) pancreatectomies with IAT. Forty percent of patients were insulin free after a mean followup of 18months (range 1 to 46months). Factors associated in univariate analyses with insulin independence included female gender (p=0.004), lower body weight (kg) (p=0.04), more islet equivalents per kg body weight (IEQ/kg) transfused (5months followup (n=32), 23 (72%) are narcotic free, with a substantial decrease in ME usage (p=0.01). The likelihood of glycemic control after IAT is related to both patient characteristics and islet cell mass. Based on these data, more islet cells may be required for insulin independence than previously thought.