The SA Journal Diabetes & Vascular Disease Vol 13 No 1 (July 2016)

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VOLUME 13 NUMBER 1 • JULY 2016 17
SA JOURNAL OF DIABETES & VASCULAR DISEASE RESEARCH ARTICLE
Study of the effect of altitude on the measurement of
glycated haemoglobin using point-of-care instruments
SANDRA W VEIGNE, EUGENE SOBNGWI, BRICE E NOUTHE, JOELLE SOBNGWI-TAMBEKOU, ERIC
V BALTI, SERGE LIMEN, MESMIN Y DEHAYEM, VICKY AMA, JEAN-LOUIS NGUEWA, MAIMOUNA
NDOUR-MBAYE, ALIOUNE CAMARA, NABY M BALDE, JEAN-CLAUDE MBANYA
Correspondence to: Eugene Sobngwi
Sandra W Veigne, Brice E Nouthe, Eric V Balti, Serge Limen, Mesmin Y
Dehayem, Vicky Ama, Jean-Louis Nguewa, Jean-Claude Mbanya
National Obesity Centre, Yaoundé Central Hospital and Faculty of Medicine
and Biomedical Sciences, University of Yaoundé 1, Yaoundé, Cameroon
e-mail:
Eugene Sobngwi, Jean-Claude Mbanya
Molecular Medicine and Metabolism Laboratories, Biotechnology Center,
University of Yaoundé 1, Yaoundé, Cameroon
Brice E Nouthe
Department of Medicine, McGill University, Montreal, Quebec, Canada
Joelle Sobngwi-Tambekou
Centre of Higher Education in Health Sciences, Catholic University of
Central Africa, Yaoundé, Cameroon
Eric V Balti
Diabetes Research Center, Faculty of Medicine and Pharmacy, Brussels Free
University-VUB, Brussels, Belgium
Maimouna Ndour-Mbaye
Cheick Anta Diop University, Dakar, Senegal
Alioune Camara, Naby M Balde
University Teaching Hospital of Donka, Conakry, Guinea
Jean-Claude Mbanya
University of Technology, Kingston, Jamaica
Previously published in Cardiovasc J Afr 2015; 26(1): 38–40
S Afr J Diabetes Vasc Dis 2016; 13: 17–19
Abstract
We measured the glycated haemoglobin (HbA1c) levels of
a total of 24 non-diabetic volunteers and diabetic patients
using a point-of-care (POC) analyser in three Cameroonian
cities at different altitudes. Although 12 to 25% of duplicates
had more than 0.5% (8 mmol/mol) difference across the
sites, HbA1c values correlated significantly (r = 0.89–0.96).
Further calibration studies against gold-standard measures
are warranted.
Keywords: glycated haemoglobin, altitude, diabetes
Introduction
HbA1c concentration is used for the appropriate diagnosis and
management of diabetes,1,2 but the standard way of measurement
requires an expensive and time-consuming ion-exchange, high-
performance liquid chromatography (HPLC) technology. Point-of-
care (POC) instruments represent a cheaper alternative to determine
HbA1c levels in five to 10 minutes. They can be used by non-
laboratory staff to tailor a patient’s care and educational messages
to HbA1c values and clinical findings in a one-stop-shop approach.3,4
Their potential shortcomings include cases of haemoglobinopathy
or some environmentally linked limitations.5,6
While operating temperature and humidity are easily controlled,
altitude cannot be standardised for operation. We investigated
the performance of one of the most commonly used POC
HbA1c instruments in African clinical settings, situated at varying
altitudes.
Methods
In this cross-sectional study, HbA1c concentrations were measured in
three cities of Cameroon in blood samples simultaneously collected
from the same individuals. The study settings were Douala (13-m
altitude), Yaounde (650-m altitude), and Bamenda (1 600-m
altitude).
The study was approved by the National Ethics Committee of
Cameroon. All participants gave their informed consent.
The study participants were 24 volunteers distributed in four
groups: six non-diabetic (healthy) volunteers [no clinical symptoms,
fasting glycaemia < 1.26 g/dl (6.99 mmol/l) and HbA1c levels < 6.6%
(< 49 mmol/mol)], six patients with diabetes with HbA1c levels <
6.6% (< 49 mmol/mol), six patients with HbA1c levels at 6.6–8.0%
(49–64 mmol/mol) and six patients with HbA1c levels > 8.0% (> 64
mmol/mol).
All patients had to have had diabetes for at least one year,
with stable treatment and HbA 1c values over at least three months
preceding the study defined by HbA1c variation < 1% between two
measurements. Exclusion criteria included any haemoglobinopathy,
recent malaria, haematological disorder or any other acute medical
condition in the preceding month, total haemoglobin level > 11 g/
dl, and creatinine clearance < 60 ml/min.
Volunteers were invited, and after informed consent, we
conducted an interview, clinical examination and biochemical
investigations for the ascertainment of eligibility. Collections of
venous blood in eligible participants were all done the same day
from an antecubital vein in four EDTA tubes stored in refrigerated
containers for all three assays.
The blood samples collected on the same day for each participant
were immediately transported by car to the target settings in a
refrigerated container. The room temperature was standardised for
all study sites at 25°C, and humidity was maintained between 45
and 60%.
HbA1c measurements were performed using the In2it POC device
(Bio-Rad laboratories, Deeside, UK), which was calibrated prior to
the study, with all reagents from the same lot (072T128). The same
operator performed the assays in each of the settings within 48
hours of blood collection. All manipulations were done following
the operating procedure of the manufacturer in order to reduce the
variability of the measurements.