Natasha Armaghanian1,2,3, Julie Hetherington4, Venkat Parameswaran5,6, Elizabeth L Chua7,8, Tania P Markovic9,10, Jennie Brand-Miller11, Kate Steinbeck1,2. 1. Academic Department of Adolescent Medicine, Children's Hospital at Westmead, Sydney, Australia. 2. Discipline of Child and Adolescent Health, University of Sydney, Sydney, Australia. 3. Department of Respiratory Medicine, Royal Prince Alfred Hospital, Sydney, Australia. 4. Endocrinology and Metabolism Centre, Royal Prince Alfred Hospital, Sydney, Australia. 5. Department of Diagnostic Endocrinology, Royal Hobart Hospital, Hobart, Australia. 6. School of Medicine, University of Tasmania, Hobart, Australia. 7. Department of Endocrinology, Royal Prince Alfred Hospital, Sydney, Australia. 8. Central Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, Australia. 9. Boden Collaboration for Obesity, Nutrition, Exercise and Eating Disorders, University of Sydney, Sydney, Australia. 10. Department of Endocrinology, Metabolism and Obesity Service, Royal Prince Alfred Hospital, Sydney, Australia. 11. School of Life and Environmental Sciences and Charles Perkins Centre, University of Sydney, Sydney, Australia.
Abstract
BACKGROUND: Hypoglycemia in cystic fibrosis (CF), in the absence of glucose-lowering therapies, has long been identified as an important issue in the management of CF. There is currently still no unifying hypothesis for its etiology. AIM: The aims of this study were to perform a 3-h oral glucose tolerance test (OGTT) in participants with CF and (1) document glucose, insulin, glucagon, glucagon-like-peptide-1 (GLP-1), and glucose-dependent insulinotropic peptide (GIP) release patterns within varying glucose tolerance groups during the OGTT; (2) determine the prevalence of hypoglycemic during the OGTT; and (3) define any association between hypoglycemia and patterns of insulin, glucagon, GLP-1, and GIP release. METHODS: Eligible participants attending an adult CF clinic completed a 3-h OGTT. Hypoglycemia on OGTT was defined as mild (glucose 3.4-3.9 mmol/L), moderate (glucose 3.1-3.3 mmol/L), and severe (glucose ≤ 3 mmol/L). Hormones were measured at fasting, 30, 60, 120, and 180 min. RESULTS: Twenty-four participants completed the study, of which 7 had normal glucose tolerance, 12 had abnormal glucose tolerance, and 5 had cystic fibrosis related diabetes (CFRD). All participants had a delayed insulin response compared with normative data. All glucose tolerance groups showed appropriate and similar suppression of fasting glucagon. Four participants (17%) had mild hypoglycemic, three (13%) had moderate hypoglycemic, and eight (33%) had severe hypoglycemic. No participant with CFRD demonstrated hypoglycemic. Of the 19 participants without CFRD, 15 (79%) experienced hypoglycemic. Participants with hypoglycemic had greater peak glucose and insulin responses than those that did not have hypoglycemic, and this approached significance (p = .0625 for glucose and p = .0862 for insulin). No significant mean differences between GLP-1 and GIP release were found. There was no relationship between hypoglycemic and modulator therapy. CONCLUSION: Postprandial hypoglycemic was unmasked by the extension of an OGTT to 3 h. Delayed and abnormal insulin release, and ineffective counter-regulatory action of glucagon may have a role in its etiology.
BACKGROUND: Hypoglycemia in cystic fibrosis (CF), in the absence of glucose-lowering therapies, has long been identified as an important issue in the management of CF. There is currently still no unifying hypothesis for its etiology. AIM: The aims of this study were to perform a 3-h oral glucose tolerance test (OGTT) in participants with CF and (1) document glucose, insulin, glucagon, glucagon-like-peptide-1 (GLP-1), and glucose-dependent insulinotropic peptide (GIP) release patterns within varying glucose tolerance groups during the OGTT; (2) determine the prevalence of hypoglycemic during the OGTT; and (3) define any association between hypoglycemia and patterns of insulin, glucagon, GLP-1, and GIP release. METHODS: Eligible participants attending an adult CF clinic completed a 3-h OGTT. Hypoglycemia on OGTT was defined as mild (glucose 3.4-3.9 mmol/L), moderate (glucose 3.1-3.3 mmol/L), and severe (glucose ≤ 3 mmol/L). Hormones were measured at fasting, 30, 60, 120, and 180 min. RESULTS: Twenty-four participants completed the study, of which 7 had normal glucose tolerance, 12 had abnormal glucose tolerance, and 5 had cystic fibrosis related diabetes (CFRD). All participants had a delayed insulin response compared with normative data. All glucose tolerance groups showed appropriate and similar suppression of fasting glucagon. Four participants (17%) had mild hypoglycemic, three (13%) had moderate hypoglycemic, and eight (33%) had severe hypoglycemic. No participant with CFRD demonstrated hypoglycemic. Of the 19 participants without CFRD, 15 (79%) experienced hypoglycemic. Participants with hypoglycemic had greater peak glucose and insulin responses than those that did not have hypoglycemic, and this approached significance (p = .0625 for glucose and p = .0862 for insulin). No significant mean differences between GLP-1 and GIP release were found. There was no relationship between hypoglycemic and modulator therapy. CONCLUSION: Postprandial hypoglycemic was unmasked by the extension of an OGTT to 3 h. Delayed and abnormal insulin release, and ineffective counter-regulatory action of glucagon may have a role in its etiology.