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Diabetes - Type 2
Type 2 diabetes is considered a ‘modern lifestyle’ disease, often
associated with inactivity and obesity. Commonly referred to as ‘mature
onset’, it is usually diagnosed in people over 45 years of age, but is
increasingly being noted in younger people. As the obesity epidemic
hits the Western world, the cases of teenagers developing type 2
diabetes are becoming alarmingly frequent.
In 2003, the countries with most people with diabetes were: India
(35.5 million), China (23.8 million), the United States (16 million),
Russia (9.7 million) and Japan (6.7 million).
There are approximately half a million people with diagnosed
diabetes in Australia and many more who are undiagnosed. In the last 20
years, the number of Australians diagnosed with diabetes has trebled
and 275 people develop diabetes every day.
At least three quarters of the estimated 150 million diabetics world-wide are type 2 and the World Health Organisation expects numbers to double to over 300 million by 2025.
Type 2 diabetes occurs because some people cannot respond normally
to the insulin they make (unlike type 1 diabetes which is characterised
by the body not producing enough insulin). This results in high
concentrations of glucose in the blood, which can damage many of the
body’s systems, especially blood vessels and nerves.
Insulin is an important hormone made in the human pancreas – a small
organ that sits close to the intestine. Insulin regulates the body’s
use of glucose (sugar), which is one of our major energy sources.
Insulin is particularly important after we eat a meal when glucose
enters the blood stream from the intestine. The elevation in blood
glucose at this time triggers the release of insulin from the pancreas.
Insulin then travels through the blood and assists the transfer of
glucose from blood into cells so it can be used for energy.
There is now evidence of an underlying genetic predisposition for
type 2 diabetes, with some genes consistently associated with an
increased risk of developing the condition. The inability of the body
to utilise glucose (insulin resistance) is strongly correlated with
waist measurements and abdominal fat levels. Garvan’s research shows
that fat directly around organs in the stomach, rather than fat under
the skin, is a major risk factor. If left untreated, diabetes can cause
serious long-term complications including kidney disease retina damage,
cardiovascular disease and nerve damage, often resulting in
amputation.
You are in a high-risk category of developing type 2 diabetes if you
fit any of the following criteria:
- Over 45 years of age, overweight and/or have a high blood
pressure
- Over 45 years of age and have a family member with diabetes
- Have heart disease or have suffered a heart attack
- Have/had high blood glucose levels or have impaired glucose
tolerance
- Have/had gestational diabetes
- Are overweight (i.e. have a Body Mass Index higher than 25)
Type 2 diabetes develops gradually, so sometimes symptoms often go
unnoticed. These may include frequent urination, thirst, blurred
vision, skin infections, slow healing, tingling and numbness in the
feet. Sometimes no symptoms are noticed at all or the individual
assumes that they are part of the normal ageing process. Either a
Fasting Blood Glucose (FBG) or Oral Glucose Tolerance Test (OGTT)
ordered by a doctor, are used to make a diagnosis.
The first recommended action for someone with type 2 diabetes is to
reduce their body mass index. This may involve taking weight loss
medication. Increased exercise and a healthy diet can prevent the more
serious health problems that often occur in people with diabetes, such
as heart disease, stroke, high blood pressure, circulation problems,
nerve damage, and damage to the kidneys and eyes. The appearance and
severity of these complications is dependent on the duration of type 2
diabetes and can be delayed or even prevented by early detection and
treatment.
Garvan’s diabetes researchers aim to identify the molecular
mechanisms underlying the condition and are tackling the problem
through the use of genetic approaches, animal models, and clinical
studies.
We now know that there are many genes involved in the development of
type 2 diabetes and they may trigger the disease only if there is a
strong environmental influence. We are conducting a series of DNA
studies on human abdominal fat samples to find the key genes involved
in the body’s inability to process glucose (insulin resistance). There
are proteins in our cells that receive and transmit messages to and
from other cells. Garvan scientists isolated & showed that one of
these proteins PKC is a key player in regulating removal of glucose
from the blood. When PKC is blocked, the body is protected against the
development of a prediabetic condition, despite fat consumption and low
levels of physical activity.
An array of molecular and clinical studies have allowed us to establish
that the generalised inflammation in people with type 2 diabetes, which
contributes to the increased risk of cardiovascular disease, is not
present in pre-diabetes; findings that allow us to gain insights into
the steps involved in diabetes development.
Other Garvan scientists are working in collaboration with colleagues at
the Shanghai Institute of Biological Sciences to study the effects of
Chinese herbal medicines on the treatment of type 2 diabetes, and
scientifically investigate the effect of key plant compounds. Our
global approach to tackling diabetes is highlighted by our role in
establishing an Asia Pacific diabetes and obesity study group to
facilitate researcher interaction and greater outcomes for
consumers.
Yet another discovery at Garvan is a genetically engineered mouse that
eats more without gaining weight. As a result of having less fat, the
mouse also displays enhanced insulin action and an improved ability to
process blood sugar, making it more resistant to type 2 diabetes. This
finding provides a new avenue for the discovery of compounds that would
allow people to eat more without gaining weight, by converting food to
energy instead of storing it as fat. It also enables us to develop new
approaches to address our genetic risk factors as well as the
better-known environmental ones.
News
My Genes Made Me Eat That: Are Our Parents to Blame for Our Body Size?
MEDIA RELEASE:
15 Dec 2009
Genetic influences on appetite and weight are profound and may pave the way toward more targeted and effective therapies for weight management says Professor Stephen O’Rahilly from Cambridge University, giving a free public lecture on the genetics of obesity tonight at Garvan.
Research Fellowship announcement to support link between weight loss and the reversal of Type 2 diabetes
MEDIA RELEASE:
27 Oct 2009
Associate Professor Katherine Samaras is the new recipient of the GlaxoSmithKline (GSK) Don Chisholm Diabetes Research Fellowship. The Fellowship is dedicated to funding vital research into the causes, processes and treatments for Type 2 diabetes, one of Australia’s most common and serious diseases – and is named in honour of Professor Don Chisholm, who is recognised as a leader in clinical diabetes research.
The free radical that triggers insulin resistance and Type 2 diabetes
MEDIA RELEASE:
28 Sep 2009
Garvan scientists have found that overeating may stimulate the conversion of the oxygen in the air we breathe into toxic free radicals, leading to insulin resistance and Type 2 diabetes. Until now, no-one has identified the central mechanism, or cellular switch, that initiates insulin resistance.
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