| Research Article |
Open Access |
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| Prevalence of Diabetes Mellitus and Impaired Glucose Tolerance in
Luanda - Angola |
| Antonio Dias Evaristo-Neto, Maria Cristina Foss-Freitas and Milton Cesar Foss* |
| School of Medicine of Ribeirão Preto-USP, Brazil |
| *Corresponding author: |
Milton Cesar Foss
Professor of Medicine
School of
Medicine of Ribeirão Preto-USP, Medicine
Av. Bandeirantes 3900, Ribeirão Preto
São Paulo 14049-900, Brazil
Tel: +55(16)36022467
Fax: +55(16)36336695
E-mail:
mcfoss@fmrp.usp.br |
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| Received July 10, 2012; Accepted August 04, 2012; Published August 09, 2012 |
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| Citation: Evaristo-Neto AD, Foss-Freitas MC, Foss MC (2012) Prevalence of
Diabetes Mellitus and Impaired Glucose Tolerance in Luanda - Angola. J Diabetes
Metab 3:209. doi:10.4172/2155-6156.1000209 |
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| Copyright: © 2012 Evaristo-Neto AD, et al. This is an open-access article
distributed under the terms of the Creative Commons Attribution License, which
permits unrestricted use, distribution, and reproduction in any medium, provided
the original author and source are credited. |
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| Abstract |
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| Aim: To determine the prevalence of diabetes mellitus (DM) and impaired glucose tolerance (IGT) in Luanda, an
urban community of Angola-Africa. |
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| Methods: A random sample of 709 subjects aged 30 to 69 years (52% women) was selected from Ingombota
municipality. This cross-sectional home survey was conducted from March 2009 to April 2011, using a sampling
design of stage conglomerates. A two-stage survey was carried out. First, clinical and anthropometric data were
obtained and fasting capillary glucose level was determined. The cut-off point was 5.55 mmol/l. Subjects who
screened positive (fasting capillary glucose ≥ 5.55 mmol/l and <11.1 mmol/l) and each sixth consecutive subject who
screened negative (fasting capillary glucose <5.55 mmol/l) were submitted to the second phase of survey, consisting
of the 75g oral glucose tolerance test (75 g OGTT). Data was analyzed using SAS statistical software. |
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| Results: The prevalence rates of diabetes mellitus and IGT were 7.1% and 12.9%, respectively. The age group
with the highest frequency of diabetes was 60 to 69 years (33%) followed by the age group 40 to 49 (30%). The
frequency of impaired glycemic homeostasis increased with aging both in men and women. Overweight and obesity
were usual findings in the majority of subjects with diabetes (62%) and subjects with impaired glucose tolerance
(61.9%). |
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| Conclusions: The prevalence of diabetes mellitus was classified within an intermediary range (7.1%) and the
prevalence of impaired glucose tolerance is within an high range, suggesting a future increase in the frequency of
diabetes in this population. |
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| Keywords |
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| Dyslipidemia; Diabetes mellitus; Glucose tolerance |
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| Introduction |
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| The risk factors for diabetes vary around the world, but the major
risk factors in sub-Saharan Africa are similar to those in other parts
of the world. The rising prevalence in diabetes is ascribed to lifestyle
changes and urbanization, with the data now showing that the strongest
and more consistent risk factors are obesity and weight gain. Upperbody
obesity is a risk factor for diabetes, and the obesity rates in some
urban areas of sub-Saharan Africa are already approaching those of
the Western countries [1-3]. Demographic transition, epidemiological
transition have occurred in developing countries as they become
economically more resourceful, causing significant shifts in dietary
and physical activity patterns (nutritional and lifestyle transitions, and
stress). These changes cause significant effects on body composition and
metabolism, often resulting in increase in body mass index, abdominal
obesity and increase in dyslipidemia and diabetes [4]. The prevalence
of type 2 diabetes is high among Africans Americans, Afro-caribbeans
and among African migrants in Europe, all of them sharing genetic
ancestry with black Africans [5,6]. Many African countries now face
a double disease burden, with increasing number of patients with noncommunicable
diseases, such as hypertension, stroke, coronary heart
disease and diabetes, in addition to communicable diseases [7]. Africa
is experiencing one of the most rapid demographic and epidemiological
transitions of the world history [2,8]. Quantifying the prevalence of
diabetes and the number of people affected with diabetes is important
for rational planning and adequate allocation of resources [9,4]. |
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| The main objective of this population-based study was to determine
the prevalence of diabetes mellitus and impaired glucose tolerance in
Luanda-Angola/Africa. We also investigated the associations of glucose
metabolism disturbances with body adiposity. |
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| Methods |
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| A cross-sectional study was conducted in Ingombota municipality,
an urban community representative of Luanda, the capital of Republic
of Angola. Luanda is a cosmopolitan city and its estimated population is
of 6 million with a predominant Bantu ethnic group. Medical students
were trained as interviewers. Administrative authorities of Ingombota
municipality agreed with the study and the population was informed
and invited to participate through meetings. The minimum sample
size of 700 people was calculated by estimating a possible prevalence
of diabetes of 5%, with an acceptable 95% CI and 2% maximum error.
Sampling was undertaken using the conglomerate stage. We randomly
selected two villages of Ingombota municipality. A two-stage survey was
carried out. First, men and non-pregnant women aged 30 to 69 years
were invited to participate in the study. After informed written consent
was obtained, selected participants were asked to fast overnight. On the
next day, a standard questionnaire was applied and the subjects were
then submitted to medical examination including the determination of
anthropometric (weight, height, BMI=W(kg)/H2(m)) data. Capillary
blood from a finger puncture was immediately analyzed for fasting blood glucose concentration by glucose oxidase method using a
portable electronic blood glucose monitor (Accu Chek Advantage®)
with commercially available strips (Dextrotix®). |
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| Individuals with fasting capillary glycemia (FCG) ≥ 5.55 mmol/l
and <11.1 mmol/l (positive screening test) were immediately submitted
to a 75 g oral glucose tolerance test and capillary glucose was measured
2 hours later (second phase of the study). Every sixth consecutive
individual who screened negative (FCG <5.55 mmol/l) was also
submitted to the glucose load test. Previously-diagnosed individuals
and those with fasting or two-hour capillary glycemia ≥ 11.1 mmol/l
were considered to have diabetes mellitus. Individuals with two-hour
capillary glycemia ≥ 7.77 mmol/l and <11.1 mmol/l were considered
to have impaired glucose tolerance (IGT) and those with FCG <7.77
mmol/l were considered to have normal glucose tolerance. BMI
between 20.0 and 24.9 was considered normal, 25 to 29.9 overweight
and equal or higher than 30 obese. |
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| Data were analyzed using the SAS statistical software. The results
are shown as mean and standard deviation or as percentage. A logistic
regression was made for diabetic group and impaired glucose tolerance
group. The level of statistical significance was set at 5%. |
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| Results |
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| A total of 998 subjects were enrolled but because of a fear of
HIV analysis or not at home on the day of the interview, 709 subjects
participated in the study. The response rate was 71%, which indicates a
moderated cooperation of the eligible participants. Thus, 709 subjects
participated in the first phase of the study and 220 (31%) in the second
phase, 85 (38.6%) of them as control (corresponding to the each sixty
consecutive subject who screened negative). The mean age of the 709
subjects (52% female) was 46.8 ± 10.9 years old with the majority of
them within the young age groups. |
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| Of the 709 subjects tested, 50 (7.1%) were diagnosed with diabetes
mellitus, 92 (12.9%) as having impaired glucose tolerance and 567 (80%)
were classified as individuals without impaired glucose homeostasis.
The overall prevalence of diabetes mellitus in this study was 7.1% (95%
CI 5.2-8.9) and the overall prevalence of impaired glucose tolerance
was 12.9% (95% CI 10.5-15.4) (Table 1). Among 50 individuals who
met the criteria for diabetes mellitus, 64% were females and 36% were males. Diabetes was diagnosed by the determination of fasting blood
glucose in 32 subjects (64%) and by the 75 g oral glucose tolerance
test in the remaining 18 subjects (36%). Previously diagnosed diabetes
mellitus was known by 23 participants (46% of all affected subjects with
diabetes). Impaired glycaemic homeostasis appeared to be related to
aging (Figure 1), but women presented a slight higher relative frequency
of diabetes than men (8% vs. 6%) (Figure 2). Diabetes frequency increase
with aging but females present a significant increase in frequency in the
oldest age-group (Figure 3). According to the logistic regression, aging
and female gender appeared to be determinant factors for diabetes and
impaired glucose tolerance (Tables 2 and 3). |
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Table 1: Prevalence of diabetes mellitus and impaired glucose tolerance in a
sample of population aged 30 to 69 years old from Luanda/Angola-Africa. |
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Figure 1: Frequency of impaired glycaemic homeostasis from the sample of
Luanda population, according to the age-group. |
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Figure 2: Frequency of impaired glycaemic homeostasis from the sample of
Luanda population, according to the gender. |
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Figure 3: Frequency of diabetes mellitus from a sample of Luanda population,
according to gender and age. |
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Table 2: Logistic regression results of the groups of patients with diabetes and
normals from the sample of Luanda population aged 30 to 69 years. |
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Table 3: Logistic regression results of the groups of patients with IGT and normals
from the sample of Luanda population aged 30 to 69 years. |
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| Although the mean values of anthropometric data verified in the
studied sample were within the normal range, subjects with impaired
glucose tolerance or diabetes mellitus had slightly higher values than
those observed in the subjects without diabetes mellitus or impaired
glucose tolerance. Overweight and obesity were present in 62% of the
individuals with diabetes mellitus while 61.9% of the individuals with
impaired glucose tolerance showed overweight or obesity. Overweight
or obesity was present in only 9.3% but overweight prevalence was
18.8%. |
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| Discussion |
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| The prevalence of diabetes mellitus and impaired glucose tolerance
in the sample of population of Luanda (7.1% and 12.9%, respectively)
were higher than that found in sub-Saharan African countries
studies carried out during nineties, except South Africa. As a result
of increasing determinant factors for non communicable diseases in
Africa, one recent study curried out in Kinshasa (capital of Democratic Republic of Congo) with same criteria, showed a diabetes prevalence
of 19.5% and IGT prevalence of 7.5% [10]. The prevalence of impaired
glucose conditions found in this study compared to that found in
the study carried out in a rural community of Angola [11] is much
higher probably because of western life style adopted in urban areas
resulting in higher prevalence of overweight and obesity. Luanda, a
cosmopolitan city is on the way of rapid urbanization and economic
growth which lead to much money available for food intake. Diabetes
coexists with other factors of metabolic syndrome, increasing the risk
of death from cardiovascular diseases. According to King and Rewers
[9], the prevalence of diabetes mellitus in the urban community studied
is moderate (3-10%) but the prevalence of impaired glucose tolerance
is within the high range (11-20%). This is the first study to evaluate
the prevalence of diabetes mellitus and IGT in an urban community
of Angola-Africa. These data are important to give an epidemiological
basis for a public health program in this country to prevent diabetes
and other morbidities. |
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| Conclusions |
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| The prevalence of diabetes mellitus was classified within an
intermediary range (7.1%) and the prevalence of impaired glucose
tolerance is within high range, suggesting a future increase in the
frequency of diabetes in this population. |
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| References |
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