VOLUME 8 NUMBER 1 • MARCH 2011
47
JOURNAL UPDATE
SA JOURNAL OF DIABETES & VASCULAR DISEASE
South African participation in study
of exenatide twice daily with TZD or
metformin highlighted in published
study
South African centres participated in the
phase 3, randomised, double-bind, placebo-
controlled, 26-week trial of exenatide in
which twice-daily exenatide was added to
TZD alone, or used in combination with met-
formin, compared to added placebo. Other
centres were in Mexico, Romania, Canada
and the United States. Doses of exenatide
were 5 mcg for the first four weeks and 10
mcg thereafter.
Recruited into the study were 165
patients with sub-optimal control, and after
a two-week, single-blind lead-in period,
they were randomly assigned (2:1) to added
exenatide or placebo. The primary endpoint
was HbA
1c
change at endpoint.
Only eight subjects were treated with
concomitant TZD alone. Exenatide reduced
HbA
1c
levels significantly more than placebo
[–0.84% (SE: 0.20) vs –0.10% (SE: 0.23),
treatment difference –0.74% (SE: 0.16),
p
<
0.001)]. Mean reductions in body weight
were similar in both treatments at endpoint
[exenatide, –1.4 kg (SE: 0.6) vs placebo,
–0.8 kg (0.7,
p
=
0.176)].
Nearly 71% of subjects had a reduction
in both HbA
1c
levels and body weight with
exenatide, compared with 54% on placebo.
The most common adverse events (exena-
tide vs placebo) were nausea (12 vs 2%,
p
=
0.037), vomiting (8 vs 0%,
p
=
0.031)
and headache (4 vs 4%). Confirmed (blood
glucose
<
3.0 mmol/l) minor hypoglycaemia
was experienced by 4 and 2% of subjects
treated with exenatide and placebo, respec-
tively. Incidence of hypoglycaemia was not
significantly different between the groups.
Source: Liutkus J, Rosas Guzman R, Norwood P, Pop L,
Northrup J,
et al
.
Diab Obesity Metabol
2010;
12
: 1058–
1065.
Vitamin D and type 1 diabetes
For many years vitamin D was defined simply
by whether or not the patient had symp-
toms of the bone disease rickets (osteoma-
lacia in adults). However, an entirely new
perspective on vitamin D has arisen from
the observation that serum levels of the
main circulating form of vitamin D (250 HD
3
)
as high as 75 nM correlate inversely with
parathyroid hormone. This has prompted
the introduction of a new term, vitamin D
insufficiency, defined by serum levels of 250
HD
3
that are sub-optimal (
<
75 nM) but not
necessarily rachitic (
<
20 nM).
Unlike serum concentrations of 1.25
(OH)
2
D
3
, which are primarily defined by the
endocrine regulators of the vitamin D acti-
vating enzyme, I alpha-hydroxylase, circulat-
ing levels of 25 OHD
3
are a direct reflection
of vitamin D status, which for any given
individual depends on access to vitamin
D, either through exposure to sunlight or
through dietary intake.
The net effect of this is that vitamin D
status can vary significantly in populations
depending on geographic, social or eco-
nomic factors. As a result of these new
parameters for vitamin D status, a consen-
sus statement from the 13th Workshop on
Vitamin D concluded that vitamin D insuf-
ficiency was a worldwide epidemic. More-
over, recent studies have shown that in the
last 10 years alone, serum vitamin D levels
have on average fallen by 20%.
Published reports suggest that there is a
link between vitamin D deficiency and type
1 diabetes. Low circulating levels have been
seen in adolescents at the time of diagnosis
of type 1 diabetes, while there are increased
data documenting the beneficial effects
of vitamin D supplementation protecting
against type 1 diabetes. Disease severity of
patients with diabetes is increased under
conditions of dietary vitamin D restriction.
Genetic variations of the CYP27b1 gene
for the vitamin D receptor also affect sus-
ceptibility to type 1 diabetes, while other
gene haplotypes of the vitamin D receptor
seem to confer protection against diabetes.
Future studies are needed to focus on the
beneficial effects of supplementary vitamin
D with respect to infectious and autoim-
mune diseases.
Source: Hewison M.
Endocrinol Metabol Clin N Am
2010;
39
: 365–379. DOI: 10.1016/j.ecl.2010.02.010.
J Aalbers, Special Assignments Editor
SOLGAR
Vitamins |
INNOVATION AND QUALITY
Since 1947
CAREFULLY MANUFACTURED
in the USA
BY SOLGAR LABORATORIES
Available from Independent Health stores and Healthcare practitioners
For more information email
|
| Tel 011 462 1652
At Solgar,
QUALITY ISN’T A WORD WE
USE CASUALLY
-
It’s a way of life.
IT HAS BEEN OUR GUIDING PRINCIPLE
since 1947
AND IS DEEPLY INGRAINED
IN EVERY STEP WE TAKE.
