Assessment of the Severity of Hypoglycemia and Glycemic Lability in Type 1 Diabetic Subjects Undergoing Islet Transplantation

Assessment of the Severity of Hypoglycemia and Glycemic Lability in Type 1 Diabetic Subjects Undergoing Islet Transplantation Edmond A. Ryan 1 , Tami Shandro 1 , Kristy Green 1 , Breay W. Paty 1 , Peter A. Senior 1 , David Bigam 2 , A.M. James Shapiro 2 and Marie-Christine Vantyghem 3 1 Department of Medicine, Clinical Islet Transplant Program, University of Alberta and Capital Health Authority, Edmonton, Alberta, Canada 2 Department of Surgery, Clinical Islet Transplant Program, University of Alberta and Capital Health Authority, Edmonton, Alberta, Canada 3 ERIT-M 0106 (Diabetes Cell Therapy), Institut National de la Santé et de la Recherche Médicale/Endocrinology and Metabolism Department, Lille University Hospital, Lille, France Address correspondence and reprint requests to Edmond A. Ryan, 362 Heritage, Medical Research Centre, Edmonton, Alberta, Canada T6G 2S2. E-mail: edmond.ryan{at}ualberta.ca Abstract Currently, the major indications for solitary islet transplantation are recurrent severe hypoglycemia and labile glucose control. Quantifying these problems remains subjective. We have developed a scoring system for both hypoglycemia and glycemic lability, established normative data, and used them in patients who have undergone islet transplantation. A composite hypoglycemic score (HYPO score) was devised based on the frequency, severity, and degree of unawareness of the hypoglycemia. In addition, using 4 weeks of glucose records, a lability index (LI) was calculated based on the change in glucose levels over time and compared with a clinical assessment of glycemic lability. A mean amplitude of glycemic excursions (MAGE) was also calculated based on 2 consecutive days of seven readings each day. These scores were determined in 100 randomly selected subjects with type 1 diabetes from our general clinic to serve as a control group and in patients before and after islet transplantation. The mean age of the control diabetic subjects was 38.4 ± 1.3 years (±SE), with a duration of diabetes of 21.5 ± 1.1 years. The median HYPO score in the control subjects was 143 (25th to 75th interquartile range: 46–423). The LI in the diabetic control subjects was 223 (25th to 75th interquartile range: 130–329 mmol/l 2 /h · week −1 ). The LI correlated much more closely than the MAGE with the clinical assessment of lability. A HYPO score of ≥1,047 (90th percentile) or an LI ≥433 mmol/l 2 /h · week −1 (90th percentile) indicated serious problems with hypoglycemia or glycem