Asia's diabetes time bomb3rd June 2009
Diabetes is on the rise worldwide, according to new research, with more than half of new diabetes cases likely to occur in Asia.
In India, where there are currently 40 million cases of diabetes, it is predicted that the numbers will swell to 70 million.
In China, where the numbers are similar, with 39 million cases, they are predicted to grow to 59 million.
The number of diabetics is also expected to rise in Bangladesh from 3.8 million to 7.4 million, with similar patterns for Indonesia, the Philippines, Malaysia, Vietnam, and other countries.
Low and middle income countries will be the most affected by the diabetes boom, researchers said.
Basing their findings on the analysis of hundreds of articles, data and studies published between January 1980 and March 2009, the researchers predict that the number of diabetics could grow by as much as one third globally in the next 15 years.
Such an increase would present a problem for booming Asian economies, as diabetes treatment is expensive.
There is also a likelihood that sufferers in Asia would be younger and skinnier than those elsewhere. Researchers blame the trend toward high urbanisation in Asia for the increase of the disease, bultural and genetic differences also play a role.
The prediction, which is based on current trends, comes as a shock because doctors had previously believed type 2 diabetes to be a consequence of obesity, diet, and age.
But while most people from Asian countries such as China and Japan are thinner than their Western counterparts, they can have a similar or even higher prevalence of diabetes than in the West.
The increasing trend in Asia is part of a wider tendency for diets and lifestyles to change across the region, and can be seen as part of a high-paced transition into modernity.
And while diabetes usually affects people between the ages of 60 and 79 years in developed countries, people currently becoming ill with diabetes in Asia are in the range of 20 and 59 years old.
Asians who become susceptible to diabetes might have a low birth weight, develop gestational diabetes in pregnancy, and tend to be over-nourished in later life.
The likelihood of gestational diabetes is two to three times higher among Asian women than it is among whites.
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Thursday 10th September 2009 @ 7:54
Impact of Ecology on Development of NIDDM
Diabetes has become a major health problem in today’s world. Complications of
diabetes and related problems are the leading causes of death in most countries.
The incidence is increasing all over the world however there is a geographical
variation. When look at the problem, you will see some characteristic features of
this increase in incidence. It is higher in cities than in villages all over the world.
What is wrong with cities?
People who migrated to other countries have high prevalence of diabetes. Ex-
Migrant Asian Indian populations have a higher prevalence of NIDDM than both
the population of India and the population of the host country.(1)
The prevalence of NIDDM is lower among Caucasian whites ,whereas in nonwhites
and people of tropical countries ,the prevalence is around 10% or more.(2)
In some population groups ,it is very much higher. The prevalence of NIDDM in
Pima Indians of Arizona is more than 50 %.( only one case of DM was found in
1908.)3 It was found that the prevalence of NIDDM in Nauru , a central pacific
island was 44%(In 1933 medical survey in Nauru no cases of diabetes had been
reported. (4)This phenomenon is seen in other population groups though not to
Why it is so?
The twin studies and family studies showed, NIDDM has strong genetic base.(5,6)
Upon urbanization, the development of DM and obesity varies among different
population groups. It has been found that upon urbanization, the incidence of
insulin resistance in the ethnic groups of tropical origin is the highest and low in
people from harsh winter habitats. The Europeans have a lower incidence. Asians
have a very high prevalence but among urbanized Asians, Japanese have a lower
prevalence. The Tibetan migrants who came from a harsh cold climate in to the
tropical part of Indian peninsula have a lower tendency to develop central obesity.
The urbanized people of Kashmir-Himalayas also have a lower prevalence of
diabetes than the rest of the urban Indians. Based on above observations, it has
been suggested people adapted to harsh winter environment for several
generations have lower tendency to develop diabetes.(7)
Although NIDDM has a strong genetic basis, the genes identified so far only
account for lee than 5% of cases of DM. Recent studies shows defect in
mitochondrial structure and function in pts with insulin resistance.(8)
Why the incidence of diabetes is increasing and why it is different among different
Several hypotheses have been proposed to explain the above. The “thrifty gene
hypothesis” proposed by James Neel, a population geneticist in 1962 drew more
attention(9). He suggested that populations highly prone to NIDDM have genes
that would have been selectively advantageous in the past during frequent
periods of prolonged starvation whereas they would be detrimental now when
have adequate and safety food supply.
This hypothesis has been challenged on several grounds.
(1) It doesn’t explain the high prevalence of diabetes among pacific populations.
They would have avoided frequent and prolonged starvation as their island with
tropical equatorial climate has luxuriant vegetations all year round and
surrounded by the sea full of fish.
(2) Thrifty genes should be more common in Europe with its less abundant
vegetations due to long harsh winter and frequent wars among different tribes
and nationalities during the history. 10
Several hypotheses have been suggested after the thrifty gene hypothesis. Not so
thrifty hypothesis, fetal origin hypothesis (thrifty phenotype), Dietary origin etc.
However none of those adequately explain the present trend. Most of these
hypothesis were based on the supply of food and nutrition at various stages of
development. Therefore , it is necessary to find a different explanation.
First, we summarize the questions, we have to find answers.
(1) Why the prevalence of diabetes is different among different population
(2) Why the incidence of diabetes is increasing?
(3) Even among the same population groups, why the prevalence is different
between villages and cities?
Diabetes has a strong genetic component and development of diabetes is a result
of gene and environmental interaction.
Then the question is what are the environmental factors /factor contribute to the
development of diabetes?
What is the influence of geography, history of mankind and evolutionary forces on
the development of diabetes?
The fossil and genetic evidence indicate that mankind originated some 200,000
years ago in east Africa. Later the man migrated to various other parts of the
world and today the man lives in almost all over the world. Unlike other animals,
man has adapted to various different climatic and environmental conditions.
During its journey from east Africa to various other parts of the world throughout
a period of 200, 000 years, man has developed various changes in the body.
Color, size, shape etc to adapt to the environmental conditions. Man had to face
and adapt to the extremes of temperature. People who live in deserts and sub-
Saharan Africa had to adapt to the warm and hot environments whereas people
who migrated to the northern Europe , arctic regions and Himalayas had to adapt
to the extreme cold environment. People who could not adapt to the harsh
environment were selected out. Even today people die of extremes of
temperature. Heat strokes and hypothermia. The environmental temperature
could have acted as a selective force.
What adaptations should have taken place to live in such such harsh
environmental conditions? For people who live in cold environment need to have
an efficient energy generation system and mechanism to conserve heat.
Therefore, having a thick subcutaneous fat is an advantageous to live in those
areas. In the history people who didn’t have thick subcutaneous fat were selected
out. Over the generations, people who live in those areas have (should have) thick
subcutaneous fat. So they will be genetically programmed to have thick
subcutaneous fat. (This is an assumption and I will have to find literature)
To generate energy, they need to have an efficient fatty acid oxidation system.
Fatty acid oxidation takes place in mitochondria and they should have efficient
mitochondrial enzyme systems to generate more energy.
When they get additional food, those fatty acids will be oxidized by those
evolutionary adapted efficient mitochondrial enzyme system and the additional
fat will be deposited in subcutaneous space. When these two mechanisms fail to
remove additional fat, those will go too deposited as visceral fat.
Recent observations showed reactivation of brown adipose tissue in adults when
they were exposed to cold environment for long periods. The resistance of
developing obesity in people living in cold climate could be account for that.
Brown adipose tissue has a higher metabolic rate.(11)
Therefore, efficient mitochondrial enzyme systems, thick subcutaneous fat,
reactivated brown adipose tissue could account for relative resistance of people
who live in cold climate.
For people who live in tropical environment, they need less energy production to
keep the body temperature constant. Over the generations their mitochondrial
enzyme system is adapted to produce low energy. When they get extra food
supply, the mitochondria can’t oxidize them all and additional fat will be
People who live in tropical climate do not need efficient energy producing
mitochondrial enzyme systems or heat conservation mechanism as for people live
in cold climate. For them having such features can be harmful. They should have
thin layers of subcutaneous fat. Their mitochondria are adapted over generations
to produce energy at a lower level. If they get abundant food supply, the
additional fatty acids will not be oxidized and are deposited in tissues. As they are
genetically programmed to have a less space for sub coetaneous fat, the
additional fat will be deposited in viscera.
In addition, (as recently found) they do not have the re activated brown adipose
tissue as people live in cold climate.
Therefore, they are more prone to develop visceral obesity than people live in
cold climate the mitochondrial enzymes are genetically determined. People live in
different climatic conditions have genes producing enzymes of different
efficiency. Thus they are genetically different. This differenc is due to evolutionary
selection out of genes whose products rate of metabolism is not suited to the
environment they live.
The genetic makeup of people who live in a certain environment over generations
for hundreds or thousands of years has well adapted to the environment.
The genes which produce traits which are not suitable to the environment have
been selected out. Like skin color or blood group, the particular genotype which
predisposed to develop diabetes was well adapted to the environment and was
normal or variant of normal for the environment they used to live. However, the
recent change in diet, life style, stresses provide more fatty acids which can’t be
sufficiently metabolized by the mitochondrial enzyme systems they inherited.
The genes which are predisposing the person to develop diabetes are responsible
for synthesis of mitochondrial proteins. Mitochondria have its own genes but
produce few proteins involved in the respiratory chain. Most of the mitochondrial
proteins are produced by nuclear genes. These proteins are called nuclear
encoded mitochondrial proteins.
In looking for candidate genes for diabetes, it is necessary to look for those genes
which encode mitochondrial proteins.
Mitochondria can involve in the causation of diabetes in two ways.
1, Defects in protein produced by mitochondrial gene. The DM produced by
mitochondrial genes show matrilineal inheritance.
2 However, the majority of DM doesn’t show matrilineal inheritance and those
could be due to nuclear genes which encode mitochondrial proteins. Identifying
genes responsible for diabetes will help to unravel the metabolic pathways which
are defective and which will help to develop drugs.
The incidence and prevalence of DM, its natural history and variant clinical
features and complications among different population groups have been well
studied. The presence of defective mitochondria in NIDDM has been published
recently. However, the cause for defective mitochondria in NIDDM has not been
I believe, the impact of ecology and temperature on genome of persons living in a
certain environment for long time and the recent change in change and life style
provide answers to the present trend.
To explore further, we need to study the ecological changes globally and the
changes in incidence and prevalence of diabetes among different population
The next question is what is the use of this hypothesis? Even if it is found to be
true, does it affect the management of patient with diabetes or prevent the
development of diabetes?
The first thing in any disease condition, we need to know why it has happened
and the causative factors for it.
The second is, it showed people who lived in different climatic conditions are
genetically and therefore biologically different. Therefore it is necessary to have
different management strategies and guidelines. The exercise, diet. And life style
changes need to be given high priority in treating or preventing diabetes in
population groups who are more susceptible to develop diabetes. It is necessary
to have different protocols for above.
Genes do not act in isolation. It interacts with other genes and environmental
factors. The action of genes or expression of genes is modified by other genes or
environment. In certain genetic conditions, even among the same family
members, the clinical manifestations vary. This is due to the effect of modifier
genes and? Some environmental factors which can modify the expression of
genes. It is important to identify factors which can modify the action of genes.
This will help to ameliorate t the clinical features and complications of the
(1)Omar MAK, Motala AA, Seedat MA et al. Southth African Indians show a high
prevalence of NIDDM and bimodality in plasma glucose distribution patterns.
Diabetes care 1994;17: 70-3
(2)Dowse G, Zimmet P,. The thrifty genotype in NIDDM. The hypothesis survives.
(3)Knowler WC, Pettitt DJ, Savage PJ, Bennett PJ. Diabetes incidence in Pima
Indians, contributions of obesity and parental diabetes. Am J Epidemiol 1981;113:
(4)Zimmet P Arblaster M, Thomas K. The effect of westernization of normal
populations, studies on a Micronesian community with a high diabetes prevalence.
Aust NZ J med 1978;8:141-6
(5)Barnett AH, Eff C, Leslie RDE,Pyke DA.Diabetes in identical twins, a study of
200 pairs.Diabeologica 1981;20:87-93
(6)Newman B,Selby JV, King MC et al. Concordaence for type 2 diabetes in male
twins. Diabetologia 1987;30:763-8
(7)Watwe M, Yajnik C. Evolutionary origins of Insulin resistance, a behavioral
switch . BMC Evol Biol 2007;7:2147-61
(8)Yongzhong W,Scott R, Thyfault JP, Ibdah JA. Nonalcoholic fatty liver disease in
mitochondrial dysfunction. World J gastroenterol 2008;14(2):193-99
(9)Neel J. Diabetes mellitus; A “thrifty” Genotype rendered detrimental by
progress. Am J Hum genet 1962;14:353-62
(10) Riccardo B. Diabetes epidemic in newly westernized populations, Is it due to
thrifty genes or to genetically unknown foods. JR Soc Med 1998; 91;622-625
(11)Nedergaard J, Bengtsson T, Cannon B. Unexpected evidence for active brown
adipose tissue in adult humans. Am J Physiol Endocrinol metab
MBBS, MD(Medicine), MSc(medical genetics)(NCL-UK)
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Title: Asia's diabetes time bomb
Author: Luisetta Mudie
Article Id: 11516
Date Added: 3rd Jun 2009