VOLUME 10 NUMBER 1 • MARCH 2013
37
SA JOURNAL OF DIABETES & VASCULAR DISEASE
DIABETES NEWS
Ethnic variations in the role of
adipose tissue on insulin resistance
in women
Compared to their white counterparts, urban
black women experience a disproportionately
higher prevalence of type 2 diabetes (T2D), as
well as higher levels of the major risk factors
of obesity and insulin resistance. Numerous
mechanisms have been postulated as to
what underlies the increased risk of T2D.
Julia Goedecke from the UCT/MRC Research
Unit for Exercise Science and Sport Medicine,
SAMRC and colleagues from the Department
of Human Biology and Department of
Medicine at UCT have published a review on
the role of adipose tissue in insulin resistance
in women of African ancestry.
1
Centralisation of body fat, specifically
increased visceral adipose tissue (VAT), is
historically one of the major determinants
of insulin resistance; whereas peripheral
subcutaneous adipose tissue (VAT) has been
shown to be ‘protective’ in predominantly
white populations. However, numerous
studies indicate that at the same level of body
mass index (BMI) or waist circumference,
black women are more insulin resistant than
their white counterparts in spite of having
less VAT and hepatic steatosis.
In white women, VAT is the most
significant determinant of insulin sensitivity,
whereas in black women this is more closely
associated with abdominal SAT. Gluteal SAT
is negatively correlated with insulin sensitivity
in black but not white women. The larger SAT
adipocyte size in black women is associated
with a reduced adipogenic capacity and a
higher expression of inflammatory genes
compared with their white counterparts.
Questions raised include whether
adipose tissue hypertrophy in black women
is associated with increased hypoxia and/
or oxidative stress in SAT and consequently
insulin resistance.
1.
Goedecke JH, Levitt NS, Evans J, Ellman N, Hume
DJ, Kotze L, et al. The role of adipose tissue in
insulin resistance in women of African ancestry.
J Obesity
2013, Article ID 952916.
.
org/10.1155/2013/952916.
Geographic variation of
hypertension in South Africa
A study arising out of the Division of
Health Sciences, University of Warwick
Medical School, Coventry, UK, examines
the geographic variation of hypertension in
South Africa.
1
Analysis of the South African
Demographic and Health Survey of 13 596
individuals older than 15 years mapped the
geographic distribution of hypertension at
the provincial level, accounting for individual
risk factors.
Overall prevalence of hypertension (blood
pressure ≥ 140/90 mmHg or self-reported
diagnosis or on medication) was 30.4%.
Higher prevalence of hypertension was sig-
nificantly associated with current smoking,
current drinking, self-reported sleep pro-
blems and the presence of cardiovascular
comorbidities such as T2D.
The North West, Free State and North-
ern Cape provinces had the highest preva-
lence of hypertension, with the lowest levels
found in Limpopo. These geographic varia-
tions suggest the potential role of socio-
economic, nutritional and environmental
factors beyond individual-level risk factors in
the development of hypertension.
1.
Kandal NB, Tigbe W, Manda SO, Stranges S.
Geographic variation of hypertension in sub-
Saharan Africa: a case study of South Africa.
Am J
Hypertens
2012;
26
(3): 382–391.
NCD risk factors in a high HIV-
prevalence rural setting
Abraham Malaza of the Africa Centre for
Health and Population Studies, University
of KwaZulu-Natal, and colleagues examined
adult hypertension and obesity in a high
HIV-prevalence rural area.
1
The prevalence of
obesity in women was 6.5 times higher than
in men, whereas prevalence of hypertension
was 1.4 times higher than in men.
Obesity was a bigger risk factor for
hypertension in men and overweight was a
risk factor for men only. The BMI of men and
women on antiretroviral treatment (ART)
was lower than that of their HIV-negative
counterparts.
The negative association of ART with
BMI could be attributed to late presenta-
tion and initiation of individuals on ART and
the associated weight loss with advanced
HIV disease progression. It is also possible
that HIV-infected persons are more in con-
tact with healthcare services, so they may
be more susceptible to adopting nutrition-
related advice.
1.
Malaza A, Mossong J, Barnighausen T, Newell ML.
Hypertension and Obesity in Adults Living in a High
HIV Prevalence Rural Area in South Africa.
PLOS
ONE
2012;
7
(10): e47761.
G Hardy
