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Islet cell transplantation improves quality of life in diabetes, hypoglycemia unawareness
Adults with type 1 diabetes and impaired hypoglycemia awareness experienced a marked reduction in severe hypoglycemic events and an improved health-related quality of life that persisted 1 year after undergoing islet cell transplantation, according to findings published in Diabetes Care.
The Clinical Islet Transplantation Consortium Protocol 07, or CIT-07, was a multicenter, phase 3 trial for patients with type 1 diabetes with a history of severe hypoglycemic events, defined as blood glucose of 54 mg/dL or less, in the year before the trial that persisted despite medical management, Eric D. Foster, PhD, clinical assistant professor in the department of biostatistics at the University of Iowa, and colleagues wrote in the study background. Patients underwent transplantation of purified human pancreatic islets and were followed for 1 year for the primary composite endpoint of reaching an HbA1c of 7% or less and no recorded severe hypoglycemic events from day 28 to 365 after initial procedure.
In a separate analysis, the researchers observed that patients who underwent islet transplantation also experienced improvement in several domains of health-related quality of life, or HR-QOL, including a reduction in overall diabetes distress, physician-related distress, interpersonal distress and fear of hypoglycemia.
“[Patients] who participated in the CIT-07 reported significant, consistent and clinically meaningful improvements in HR-QOL,” Foster and colleagues wrote. “In particular, large decreases in both diabetes-related distress and fear of hypoglycemia were observed.”
Foster and colleagues analyzed data from 47 adults with type 1 diabetes and a history of severe hypoglycemic events in the 1 year before transplantation (mean age, 48 years; 39.6% men; mean BMI, 25.1 kg/m²; mean diabetes duration, 28.5 years; mean baseline HbA1c, 7.2%; mean baseline insulin requirement, 32.6 units per day). Participants completed four surveys — the Diabetes Distress Scale and the Hypoglycemic Fear Survey, measuring condition-specific HR-QOL, and the SF-36 and the EuroQol 5 Dimensions, measuring functional health status and health utility — before and after islet transplantation. Researchers used longitudinal mixed-effects models to assess the effect of severe hypoglycemic events on HR-QOL, functional health status and health utility after islet transplantation, as well as changes in relation to a minimally important difference threshold of half a standard deviation.
At 1 year after the initial islet transplantation, 87.5% of patients achieved the primary endpoint of HbA1c 7% or less and no reported severe hypoglycemic events, according to researchers.
In patients meeting the primary endpoint, researchers observed decreases after initial islet cell transplantation in each of the four subscales of the Diabetes Distress Scale at both 1 and 2 years (P .0012 for all). The change in total Diabetes Distress Scale score and subscale scores for emotional burden and regimen-related distress met the minimally important difference threshold of a 0.5-standard deviation change from baseline at all follow-up time points, according to researchers, as did changes in scores for the subscales of physician-related distress and interpersonal distress. Similar results were reported for the Hypoglycemia Fear Scale scores, with decreases observed for both the overall score and the two subscales (P < .0001 for all), according to researchers.
Patient self-assessments of well-being measured in the EuroQol 5 Dimensions visual analogue scale also improved between baseline and 1 and 2 years after transplantation, according to researchers. There were no between-group differences observed in patients who did or did not require continued insulin therapy after transplantation.
“Despite the acknowledged burden of immunosuppressive medications, the overall quality of life and functional health status scores after transplantation did not worsen,” the researchers wrote. “General measures of functional health status ... showed statistically significant improvements from baseline.”
The researchers noted that the observed domain improvements were predominantly among the physical health-related scales and did not meet the minimally important difference threshold, likely due to a “ceiling effect” in which pretreatment baseline scores were within overall population norms, making it less likely that clinically meaningful improvements would be observed.
“This phenomenon has been reported previously in pancreatic islet transplant recipients,” the researchers wrote. “Consistent, meaningful change is not a realistic expectation when participants enter a study at or near general population norms. If the patient population starts below the general population norms, however, as has been the case in other islet transplantation studies, meaningful improvements in general HR-QOL, functional health status and health utility are more likely.” – by Regina Schaffer
Disclosures: The National Institute of Allergy and Infectious Diseases and the National Institute of Diabetes and Digestive and Kidney Diseases, both part of the NIH, funded this study. The authors report no relevant financial disclosures.