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VOLUME 13 NUMBER 2 • DECEMBER 2016
REVIEW
SA JOURNAL OF DIABETES & VASCULAR DISEASE
The rising prevalence of hypertension in rural settings is of
great concern and probably relates to the rapid ‘urbanisation’ of
rural dwellers.
15,16
About 40% of Africans with hypertension are
undiagnosed, less than 30% of those who are diagnosed with
hypertension are on treatment, and less than 20% of those on
treatment have optimal blood pressure control (< 140/< 90
mmHg).
13,17-21
Diabetes mellitus and impaired glucose tolerance
In 2010, an estimated 12.1 million people with diabetes mellitus
(4.2% of the global estimate of 285 million) were in sub-Saharan
Africa.
22
The following year, diabetes prevalence rose to 14.7 million
(4.02% of the global 366 million). By the year 2030, there will be a
90% projected increase in diabetes prevalence in SSA, bringing the
number of Africans with diabetes to 28 million.
23
Nearly 78% of people with diabetes in sub-Saharan Africa are
undiagnosed. Heavily populated countries such as Nigeria have
three million diabetics, followed by South Africa with 1.9 million.
Fuelling the diabetes epidemic is a large pool of people with
impaired glucose tolerance (IGT), totalling an estimated 26.9 million
in 2010, and expected to rise to 47.3 million by 2030. Diabetes is
associated with a pro-coagulant state, compounding the commonly
accompanying insulin resistance and hyperinsulinaemia, and thus
contributing to accelerated atherogenesis.
Although diabetes mellitus and pre-diabetes are important
cardiovascular risk factors globally, their roles in populations
undergoing rapid epidemiological transition are unclear.
Atherosclerotic complications of diabetes are likely determined
by the pace and degree of affluence, genetic factors, phenotypic
heterogeneity of type 2 diabetes, changes in life expectancy, and
burden, duration and contribution of other cardiovascular risk
factors such as hypertension, dyslipidaemia and tobacco use. In
many parts of SSA, micro-angiopathies are the dominant chronic
complications of diabetes,
24-30
unlike in the Western world, where
macrovascular complications (MAC) predominate.
Overweight and obesity
Estimates of the prevalence of overweight and obesity vary widely
across SSA, but it is generally higher in females than in males and
particularly in southern Africa, Mauritius and Seychelles, compared
to the rest of the continent. In East and Central Africa the prevalence
of overweight (body mass index from > 25 to < 30 kg/m
2
) in women
is two to three times higher than in men (Table 1). In Ghana, males
appear to be more overweight than women. However, in much of
West Africa, southern Africa and in the islands off the east coast
of Africa, the prevalence of overweight in men is approximating
that of females. This trend towards parity indicates that overweight
is now a widespread continental problem in populations of SSA
above the age of 15 years.
However obesity still has relatively low prevalence rates
throughout SSA, ranging between 1.1 and 43.2% in females and
0.1 and 21.3% in males. Populations of southern Africa and the
islands of Mauritius and Seychelles exhibit a greater prevalence of
obesity, particularly among the women.
Physical inactivity
There are scant data on the prevalence of physical inactivity in SSA.
A WHO report of national surveys in both urban and rural settings
in five African countries (Ethiopia, Republic of Congo, Ghana,
South Africa and Zimbabwe) in 2003, involving a total of 14 725
individuals aged 18 to 69 years revealed a mean prevalence of
physical inactivity in 19.6% of men and 22.9% of women.
31
Physical inactivity was defined using the International Physical
Activity Questionnaire (IPAQ). IPAQ inactive is defined as not
meeting any of the following three criteria: three or more days of
vigorous activity of at least 20 minutes per day, accumulating at
least 1 500 MET-min per week, OR five or more days of moderate-
intensity activity or walking of at least 30 minutes per day, OR five
or more days of any combination of walking, moderate-intensity or
vigorous-intensity activities, achieving a minimum of at least 600
MET-min per week.
Across the continent, low levels of physical activity are reported in
women compared to men. According to the WHO survey, a greater
number of lazy people are found in southern Africa, Mauritius and
Seychelles, while those in the Horn of Africa and in West Africa are
relatively more physically active (Table 2, Fig. 1). This observation
closely mirrors the reported prevalence of overweight and obesity.
There are no consistent national (rural and urban) surveys for similar
years or later from other SSA countries.
The Seychelles Heart study of 2004, reported by Bovet and
colleagues in 2007, revealed a disparate prevalence of physical
inactivity, ranging from 28 to 58.6% in both genders aged 25 to
64 years, because of variable and subjective operational definitions
of physical inactivity using a modification of the WHO STEPS survey
questionnaire, which was not identical to the IPAQ.
32
More surveys
are therefore required in many SSA countries using standard
questionnaires to provide better insight of the emergence of this
cardiovascular risk factor in the continent. There are likely to be
wide variations of the levels of physical activities, determined by
culture, gender, age, occupation, socio-economic status and levels
of education.
Table 1.
Prevalence of overweight and obesity in females and males
aged 15 years and older in selected african countries by region, 2011.
Overweight Obesity
(BMI > 25 kg/m
2
, < 30 kg/m
2
) (BMI > 30 kg/m
2
)
Region/country Females (%) Males (%) Females (%) Males (%)
Eastern Africa
Uganda
UR Tanzania
23.9
28.7
8.2
16.8
1.9
3.6
0.1
0.8
Central Africa
DR Congo
Rwanda
15.8
20.7
5.7
8.1
1.1
1.6
0.1
0.1
Western Africa
Nigeria
Ghana
36.8
32.5
26.0
35.6
8.1
5.9
3.0
4.8
Southern Africa
Botswana
South Africa
53.5
68.5
41.6
41.3
17.7
36.8
6.9
7.6
Islands
Mauritius
Seychelles
56.8
73.8
44.8
63.8
22.3
43.2
8.0
21.3
DR Congo = Democratic Republic of Congo, UR Tanzania = United Republic
of Tanzania.
World Health Organisation: WHO Global Infobase:
https://apps.who.int/infobase/Comparisons.aspx (Accessed 28 December 2011). Database
updated 20/01/2011. Accessed 28 December 2011.