1. Evaluation of long-term treatment effect in a type 1 diabetes intervention trial: differences after stimulation with glucagon or a mixed meal
- Author
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Paolo Pozzilli, Irun R. Cohen, Dana Elias, Dana Peled, Itamar Raz, Merana Tamir, Rachel Eren, Shlomo Dagan, and Ann Avron
- Subjects
Adult ,Blood Glucose ,Male ,medicine.medical_specialty ,Adolescent ,Endocrinology, Diabetes and Metabolism ,Stimulation ,Glucagon ,law.invention ,Young Adult ,Randomized controlled trial ,Double-Blind Method ,Gastrointestinal Agents ,law ,Internal medicine ,Diabetes mellitus ,Insulin-Secreting Cells ,Insulin Secretion ,Internal Medicine ,medicine ,Humans ,Hypoglycemic Agents ,Insulin ,Meals ,Glycemic ,Advanced and Specialized Nursing ,Type 1 diabetes ,C-Peptide ,business.industry ,Area under the curve ,Chaperonin 60 ,Fasting ,Middle Aged ,medicine.disease ,Peptide Fragments ,Clinical trial ,Endocrinology ,Diabetes Mellitus, Type 1 ,Glucose ,Food ,Area Under Curve ,Female ,business - Abstract
OBJECTIVE Endogenous insulin secretion, measured by C-peptide area under the curve (AUC), can be tested using both the glucagon stimulation test (GST) and the mixed-meal tolerance test (MMTT). This study compares these two stimulation methods using long-term data from patients newly diagnosed with type 1 diabetes or with latent autoimmune diabetes. RESEARCH DESIGN AND METHODS A recently completed phase 3 intervention study with DiaPep277 demonstrated improved glycemic control and a significant treatment effect of glucagon-stimulated C-peptide secretion. Unexpectedly, MMTT failed to detect differences between the treated and control groups. Data from 343 patients in two balanced-randomized, double-blind, placebo-controlled, parallel-group trials of DiaPep277 were used to compare and correlate between GST- and MMTT-derived C-peptide AUC. Pearson’s correlations were calculated for absolute C-peptide AUC at baseline and 12 and 24 months and for long-term changes in AUC (∆AUC). RESULTS The absolute AUC values obtained at any single time point by the two tests were well correlated in both data sets (r = 0.74–0.9). However, the correlations between the ∆AUC were much weaker (r = 0.39–0.58). GST-stimulated C-peptide secretion was stable over the fasting glucose range permitted for the test (4–11.1 mmol/L), but MMTT-stimulated C-peptide secretion decreased over the same range, implying differences in sensitivity to glucose. CONCLUSIONS Measurement of long-term changes in stimulated C-peptide, reflecting endogenous insulin secretion, during the course of intervention trials may be affected by the method of stimulation, possibly reflecting different sensitivities to the physiological status of the tested subject.
- Published
- 2014