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Glycated haemoglobin (HbA 1c ) and fasting plasma glucose relationships in sea‐level and high‐altitude settings
Author(s) -
BazoAlvarez J. C.,
Quispe R.,
Pillay T. D.,
BernabéOrtiz A.,
Smeeth L.,
Checkley W.,
Gilman R. H.,
Málaga G.,
Miranda J. J.
Publication year - 2017
Publication title -
diabetic medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.474
H-Index - 145
eISSN - 1464-5491
pISSN - 0742-3071
DOI - 10.1111/dme.13335
Subject(s) - medicine , effects of high altitude on humans , confidence interval , altitude (triangle) , plasma glucose , confounding , concordance , endocrinology , glycated hemoglobin , diabetes mellitus , zoology , gastroenterology , type 2 diabetes , biology , mathematics , geometry , anatomy
Aim Higher haemoglobin levels and differences in glucose metabolism have been reported among high‐altitude residents, which may influence the diagnostic performance of HbA 1c . This study explores the relationship between HbA 1c and fasting plasma glucose ( FPG ) in populations living at sea level and at an altitude of > 3000 m. Methods Data from 3613 Peruvian adults without a known diagnosis of diabetes from sea‐level and high‐altitude settings were evaluated. Linear, quadratic and cubic regression models were performed adjusting for potential confounders. Receiver operating characteristic ( ROC ) curves were constructed and concordance between HbA 1c and FPG was assessed using a Kappa index. Results At sea level and high altitude, means were 13.5 and 16.7 g/dl ( P > 0.05) for haemoglobin level; 41 and 40 mmol/mol (5.9% and 5.8%; P < 0.01) for HbA 1c ; and 5.8 and 5.1 mmol/l (105 and 91.3 mg/dl; P < 0.001) for FPG , respectively. The adjusted relationship between HbA 1c and FPG was quadratic at sea level and linear at high altitude. Adjusted models showed that, to predict an HbA 1c value of 48 mmol/mol (6.5%), the corresponding mean FPG values at sea level and high altitude were 6.6 and 14.8 mmol/l (120 and 266 mg/dl), respectively. An HbA 1c cut‐off of 48 mmol/mol (6.5%) had a sensitivity for high FPG of 87.3% (95% confidence interval (95% CI ) 76.5 to 94.4) at sea level and 40.9% (95% CI 20.7 to 63.6) at high altitude. Conclusion The relationship between HbA 1c and FPG is less clear at high altitude than at sea level. Caution is warranted when using HbA 1c to diagnose diabetes mellitus in this setting.