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DIABETES RESEARCH AN D CLINICAL PRACTICE 79 (2008) S1–S127 S19
BS5-2
Incretin secretion is independent of glucokinase function
Rinki Murphy 1,2 ,P.M.Clark3,J.J.Holst4, A.T. Hattersley 1
1Insitute of Clinical & Biomedical Sciences, Peninsula Medical School,
Exeter, UK, 2Auckland Diabetes Centre, Greenlane Clinical Centre,
Auckland, New Zealand, 3Regional Endocrine Laboratory, University
Hospital Birmingham NHS Foundation Trust, UK, 4Department of
Medical Physiology, University of Copenhagen, Panum Institute,
Denmark
Aims: Incretin hormones glucagon-like peptide-1 (GLP-1) and
gastric inhibitory peptide (GIP) are released from intestinal cells
in response to luminal but not systemic glucose, and act to
potentiate glucose stimulated insulin release by the pancreatic
beta cell. Incretin secretion and function are reduced in Type 2
diabetes and are the targets of novel treatments. The enzyme
glucokinase (GCK) which is the glucose sensor in pancreatic beta
cells has also been proposed as the main glucose sensor in the
gut. Subjects with diabetes as a result of a mutation in the
GCK gene are a good model for studying this proposition. We
hypothesized that the secretion of incretins in response to a
75g oral glucose load would be lower in GCK mutation carriers
compared to controls.
Methods: We studied 79 adult subjects, 28 with GCK mutations
and 51 familial controls without diabetes. We measured glucose,
insulin, c-peptide, GLP-1 and GIP at 5 time points during a
75g OGTT (0, 30, 60, 90 and 120 minutes) and also measured
anthropometric data.
Results: GCK mutation carriers had higher mean plasma
glucose concentrations compared with non-carriers (9.9 vs 6.5
mmol/L, p<0.001). Insulin and c-peptide profiles were similar be-
tween mutation carriers and non-carriers (p=0.07 and p=0.20). GIP
and GLP-1 profiles during the OGTT were not different between
GCK mutation carriers and non carriers (p=0.70 and p=0.32). Peak
GIP or GLP-1 did not alter with age, sex, BMI or peak plasma
glucose.
Conclusions: GCK mutation carriers have higher plasma glu-
cose but equivalent insulin and c-peptide profiles during OGTT
than non-mutation carriers, consistent with reduced plasma glu-
cose sensing function of pancreatic beta cell GCK.GCK mutation
carriers had similar incretin secretion in response to 75g oral
glucose load compared with controls, suggesting that GCK is not
the main luminal glucose sensor in the gut.
BS5-3
Dexamethasone inhibits insulin stimulated glucose uptake
by reducing akt substrate of 160 kDa (AS160)
phosphorylation in human adipocytes
Sherry Ngo, Janelle Barry, John Prins, Jon Whitehead
Diamantina Institute for Cancer, Immunology & Metabolic Medicine,
University of Queensland, Brisbane, Australia
Background: Glucocorticoids are widely used in clinical ther-
apy. However, they cause adverse effects, including insulin re-
sistance and Type 2 diabetes, by as yet unclear mechanisms.
Insulin stimulates glucose uptake via the insulin receptor sub-
strate (IRS) 1/phosphoinostide-3-kinase (PI3K)/protein kinase B
(Akt) pathway and promotes the redistribution of glucose trans-
porter (GLUT) 4 from intracellular storage compartments to the
plasma membrane. Akt was reported to play a role in the late
step of GLUT4 trafficking. Akt substrate of 160 kDa (AS160) was
recently identified as a Rab-GAP involved in GLUT4 trafficking.
Insulin stimulated phosphorylation of AS160 is downstream of
Akt and appears to be essential for exposure of GLUT4 at the
plasma membrane (PM) and glucose uptake. This is mediated
through the association of phosphorylated A160 with 14-3-3
in the cytosol. We hypothesise that dexamethasone inhibits
insulin-stimulated glucose uptake at a level distal to Akt by
dys-regulation of AS160.
Methods: Differentiated human SGBS adipocytes were treated
–/+ 1 µmol/l dexamethasone for 24h –/+ co-treatment with 10
µmol/l RU486, the glucocorticoid receptor (GR) antagonist. Cells
were incubated with 1 nmol/l insulin for 20 min at 37°C to
stimulate glucose transport. Insulin-stimulated GLUT4 activity
was measured by [3H]-2-deoxyglucose uptake. GLUT4 translo-
cation was assessed by immunoblotting of PM, high and low
density membrane fractions. GLUT4 expression at the PM was
further validated using the plasma membrane lawn assay in 3T3-
L1 adipocytes. Akt activation and AS160 phosphorylation were
examined by immunoblotting using phosphospecific antibodies.
AS160 interaction with 14-3-3 was assessed by immunoblotting
of AS160 immunoprecipitates.
Results: Dexamethasone significantly inhibited insulin-
stimulated glucose uptake by ∼50% (p<0.001) in SGBS adipocytes,
but was without effect on expression or phosphorylation of prox-
imal signalling molecules (IRS-1, PI3K, Akt) or GLUT4. Dexam-
ethasone decreased insulin-stimulated translocation of GLUT4
to the PM as assessed by PM lawn assay and subcellular
fractionation/immunoblotting. AS160 phosphorylation at T642
residue (a key Akt phosphorylation site) significantly decreased
by ∼50% (p<0.01). Consequently, insulin-stimulated AS160 as-
sociation with 14-3-3 was dramatically decreased. This defect
was completely restored by RU486 indicating the involvement
of GR-mediated mechanisms. At 1 nmol/l insulin, AS160-T642
phosphorylation is maximal at sub-maximal glucose uptake
i.e. its phosphorylation is not a limiting factor. RU486 did not
completely rescue the dexamethasone-mediated inhibition on
insulin-stimulated glucose uptake.
Conclusions: Collectively, these results suggest that defects at
the level of AS160 phosphorylation contribute to dexamethasone-
induced inhibition of glucose uptake. Our finding that the
GR antagonist completely abrogates dexamethasone effect on
AS160 phosphorylation, but only partially restores glucose up-
take, are consistent with additional dexamethasone-induced
defects. AS160 presents a novel target in the improvement of
glucocorticoid-induced insulin resistance.
BS5-5
Black seed (Nigella sativa) regulates glucose, insulin level
and lipid profile in patients with Type 2 diabetes
Ahmad Bilal 1, Tariq Masud 1, Arshad Mahmood Uppal 2
1University of Arid Agriculture Rawalpindi, Pakistan, 2District Head
Quarter Teaching Hospital Rawalpindi, Pakistan
Background: Black seed (Nigella sativa (NS)) has been tried as
an anti diabetic agent in animal models of Type 2 diabetes
with considerable efficacy, but no systematic research has been
reported on humans. However NS in combination with various
herbs have been studied on human patients for the treatment of
diabetes This study investigated the effects of NS seed powder
on the levels of blood glucose, insulin and lipids in patients with
Type 2 diabetes in order to investigate possible side effects such
as a fall in leukocyte and platelet counts. This was the first ever
study of its type on human subjects that was initiated following
approval from the Directorate of Advanced Studies and Research
Board, University of Arid Agriculture, Rawalpindi, Pakistan. The
study included 46 patients with Type 2 diabetes.
Methods: Selection criteria 1) Patients of either sex with
known Type 2 diabetes. 2) Fasting blood glucose greater than
normal values, even with their usual diabetes control medicine.
3) Age between 30-60 years. 4) Patients not on insulin therapy.
5) Patients not suffering from any other chronic disease. 6) Not
taking any medication other than that for diabetes. 7) Not taking
S20 DIABETES RESEARCH AN D CLINICAL PRACTICE 79 (2008) S1–S127
black seed in any form or any other herbal treatment. 8) Preg-
nant women were not included in this study. All the registered
patients signed a consent form before the start of study. Nigella
sativa seeds were identified at “Herbarium Medicinal Botanic
Centre; Pakistan Council of Scientific and Industrial Research
(P.C.S.I.R.) Laboratories Complex, Peshawar, Pakistan”. A voucher
specimen No. (PES): 9747 was deposited there for future refer-
ence. All patients consumed NS seed powder for 40 days followed
by a placebo for another 40 days. Fasting blood samples were
collected from each subject on 0, 40th and 80th day of the study.
Glucose, insulin, total cholesterol, HDL cholesterol, LDL choles-
terol, triglycerides, total leukocyte count and platelet count were
analysed using standard methods. Data collected from all the
patients were analysed using SPSS (Statistical Package for Social
Sciences) Version-12. The results are expressed as mean ±SEM.
Where necessary, 95% confidence intervals on differences (95%
CI) are given. For each parameter, mean values were compared
by paired sample test. Correlations between different parameters
were analysed by the Chi Square test.
Results: A highly significant decrease in fasting blood glucose
(p<0.001), total cholesterol (p<0.001), LDL cholesterol (p=0.001),
triglycerides (p<0.001) and increase in insulin (p<0.001) and HDL
(p=0.011) was observed after treatment with NS seed powder. All
values except HDL reversed significantly again at the end of the
placebo phase, indicating that these changes were due to the
treatment with the NS seed powder. No significant change was
observed in total leukocyte and platelet count throughout the
study.
Conclusion: Our results demonstrate that NS seed powder
improves the levels of blood glucose and insulin and lipid profile
in patients with Type 2 diabetes with reasonable safety. We also
recommend further human studies on a pilot scale.
Diabetes in the Western Pacific region
DWP1-1
Surveillance of Type 2 diabetes in China: a subgroup
analysis of diabetes duration in the DIABCARE 2006 study
Changyu Pan 1, Wenying Yang 2, Weiping Jia 3, Jianping Weng 4,
Hui Tian 1
1Chinese PLA General Hospital, Beijing,2China-Japan Friendship
Hospital, Beijing, 3Shang Hai No.6 People’s Hospital, Shanghai, 4The
First Affiliated Hospital, Sun Yet San University, Guangzhou, China
Background and aims: The DIABCARE 2006 project, with the in-
tention of the Western Pacific Declaration on Diabetes, was a
part of DIABCARE studies initiated from 1998. DIABCARE 2006
is important for understanding current diabetes control, dia-
betes management and diabetes complications status, thereby
improving diabetes care in China.
Materials and methods: A subgroup of 2699 Chinese subjects
with Type 2 diabetes, who registered for management of dia-
betes for more than 12 months at 60 hospitals in 18 cities were
classified into three groups based on diabetes duration (years):
≤5 (n=917), 5-10 (n=801) and >10 group (n=981). Data were col-
lected on a retrospective manner by reviewing medical records,
interview and laboratory assessments. A centralised analysis
for HbA1c was carried out. All data were tabulated followed by
descriptive statistical analysis.
Results: The mean ages of subjects were 57.8, 61.7 and 65.9
years in the diabetes duration groups of ≤5, 5-10 and >10 years,
respectively. The onset age of diabetes was approximately 55
yearsinbothgroupsof≤5 years and 5-10 years, and 50 years
in the group of >10 years. The waist-hip ratio (∼0.90) and BMI
(>24.5kg/m2) were comparable in the three groups. The overall
mean HbA1c in 2006 was significantly lower than that in 1998
(8.7±2.0%). The mean HbA1c was highest in the group of >10
years (7.8±1.5%) and lowest in the group of ≤5 years (7.3±1.6%).
The percentages of subjects who achieved optimal HbA1c target
<6.5% decreased as duration of diabetes increased (≤5: 32.3%;
5-10: 22.9%; >10: 14.5%). There was also a significant improve-
ment in overall mean fasting plasma glucose (FPG) from 1998
(9.0±3.4mmol/L) to 2006 (7.7±2.5mmol/L) in all subjects. An in-
crease of more than 10% was observed in diabetes complications
when comparing subjects in the group of >10 years with the
group of ≤5 years. Our data showed more than 75% of sub-
jects with less than 10 years of diabetes used Biguanides or
Sulphonylureas as OAD therapy. Whereas, glucosidase inhibitors
(∼40%) were the most frequently used in the subjects who had
Type 2 diabetes for more than 10 years. Subjects with a longer
duration of diabetes appeared more likely to be treated with
insulin (≤5: 30.4%; 5-10: 46.3%; >10: 68.5%) and to have a longer
mean duration of insulin treatment (≤5: 1.03 years; 5-10: 1.72
years; >10: 3.05 years). The daily insulin units per kilogram
also increased with increased diabetes duration (<5: 0.44U; 5-10:
0.49U; >10 group: 0.57U). Most subjects were treated with twice-
daily injections, regardless of diabetes durations. The number of
self-monitoring blood glucose and urine glucose increased with
diabetes progression. With regards to answers about quality of
life, a preponderance percentage of subjects rated their quality of
life to be good or at least acceptable in all groups. Approximate
half of the subjects expressed psychological insulin resistance to
insulin initiation treatment.
Conclusions: An improvement in glycaemic control was ob-
served in all subgroups of diabetes durations in patients with
Type 2 diabetes. However, insulin therapy and diabetes care
were not satisfactory. The gap between therapeutic guidelines
and glycaemic control strongly indicates promoting awareness
of treat-to-target treatment and continuing medical education in
clinical practice is necessary.
DWP1-2
The individual and societal cost of Type 2 diabetes in
Vanuatu
Douglas George Falconer 1, Christopher Tarianga 2,
John Tasserei 2, Alexandra Buckley 1, Ruth Colag iuri 1.onbehalf
of the WDF Project Collaborators
1The Diabetes Unit - Australia Health Policy Institute. The University of
Sydney, NSW Australia, 2The Ministry of Health, Vanuatu
Background: Three out of four deaths in Pacific Island countries
(PICs) are due to non communicable diseases (NCDs) with Type 2
diabetes playing a critical role. The precise prevalence of diabetes
in Vanuatu is unknown but a 2005 WHO STEPS survey indicated
high rates of diabetes risk factors and diabetes prevalence is
presumed similar to other PICs e.g. Samoa (22%), Tonga (15%)
and Nauru (16%). The economic cost of NCDs in PICs is reported
to consume US$1.95 million, almost 60% of the health budget of
Tonga, and in Fiji absorbing 39% of the health budget in 2002, but
little definitive information is available on the cost of diabetes.
Aims: This study aimed to determine the individual and
societal cost of Type 2 diabetes in Vanuatu i.e. cost of treatment
(health system cost), cost to people with diabetes (out-of-pocket
expenses) and the impact of diabetes on quality of life.
Methods: This study was modelled on the Diabco$t Australia
study [1]. The “Questionnaire for Persons with Diabetes in Van-
uatu” was adapted locally to ensure relevance to the Vanuatu
health system context and culture, and was administered to a
convenience sample of 199 people with Type 2 diabetes by local
staff who were trained to conduct the survey. A self reported
survey questionnaire asked about respondents’ demographics;
health care access over the previous 3 months (such as prescrip-
tion medications, health care encounters); cost to people with