The Role of Physical Activity in the Prevention of Type 2 Diabetes
Dinesh Nagi
Mostly excerpted from
Exercise and Prevention of Type 2 Diabetes
Due to considerable expense associated with complications of type 2 diabetes.2 Primary prevention of type 2 diabetes is, therefore, of particular interest to health economists as it has in-built secondary and tertiary prevention of complications related to diabetes.
let us look at
recently published randomized trials, which have used lifestyle intervention, including physical activity, to reduce or prevent type 2 diabetes.
However, we must remember that these studies were performed in subjects at high risk of future diabetes and not in those with normal glucose tolerance.
Therefore findings of these trials may not be applicable to the population at large.
Therefore, in any community-based or public health approach to prevent diabetes and related diseases such as coronary heart disease, this is important for effective utilization of resources.
Type 2 diabetes has a number of disease characteristics which make it potentially a preventable disease.
Considerable knowledge exists about risk factors for diabetes which are potentially modifiable
Although there is a strong genetic predisposition to this disease, environmental factors play an important role in the development of clinical diabetes.
It is also clear that both insulin resistance and defective insulin secretion contribute to the development of diabetes,
Although the relative contribution of each of these two components varies in different populations and individuals within a population.
In most subjects predisposed to develop type 2 diabetes, there is generally a long but variable period during which minor degree of glucose intolerance exists
This stage of pre-diabetes can be recognized by performing an oral glucose tolerance test and is known as impaired glucose tolerance (IGT).
It can also be diagnosed by measuring fasting plasma glucose, known as impaired fasting glucose (IFG).
Subjects thus identified are at a higher risk of future diabetes compared with those whose glucose tolerance is normal.
Identification of subjects at high risk of diabetes provides us with an opportunity to modify the disease process, either to delay or prevent it from becoming clinically manifest. As in type 2 diabetes, insulin resistance and defective insulin secretion contribute to the development of IGT and IFG.
Both of these defects can be modified through lifestyle interventions and/or pharmacological therapies.
In spite of this, it has only recently been shown that type 2 diabetes can be prevented.
Behaviour modification through diet and exercise are attractive and have the added advantage of modifying other associated conditions such as coronary artery disease, hypertension, and obesity.
However, lifestyle modifications are extremely difficult to sustain over the lifetime of a given individual.
In addition, it is likely that different strategies may need to be adopted in different ethnic groups to improve adherence to measures which will promote healthy lifestyles.
It has been known for some time that physical inactivity is associated with increased risk of type 2 diabetes.
The results of various epidemiological and observational studies showed that regular physical activity had a protective effect on the development of type 2 diabetes.
These studies were remarkable for their consistent findings in the protective effects of physical activity on the occurrence of type 2 diabetes.
In addition, some of the studies also showed a dose-response relationship between the frequency of physical activity and the degree of protective effect.
These studies suggested a causative role for physical inactivity in type 2 diabetes.
the incidence of diabetes was negatively related to the frequency of exercise
. The age-adjusted risk of diabetes in men who exercised at least once a week was 0.64 compared to those who exercised less frequently.
The protective effect of exercise was unrelated to baseline body mass index (BMI) and was more marked in obese subjects.
leisure time physical activity, expressed as the number of calories expended was found to be inversely related to the development of diabetes.
The age-adjusted risk of diabetes was 6 percent lower for each 500 kcal expended.
These beneficial effects of exercise remained significant when adjusted for the confounding effects of obesity, blood pressure and parental history of diabetes.
women who participated in a vigorous physical activity at least once a week had a 33 percent lower risk of diabetes compared with those who did not take part in such activities.
in both men and women in the highest quintile of physical activity, the risk of diabetes was approximately half compared with the rest.
self-reported moderate intensity exercise undertaken for 40 min per week was associated with 56 percent lower risk of type 2 diabetes.
They also found that high levels of cardiorespiratory physical fitness (O2 consumption in a respiratory chamber) also had a protective effect on the development of diabetes.
In subjects who were at high risk of diabetes, with even a moderate degree of physical activity taken once a week for more than 40 min, the risk of diabetes was 64 percent lower than those who did not take part in physical activity.
The major concern in the use of lifestyle intervention to prevent diabetes has been around the issue of long-term sustainability of this intervention.
The study by Eriksson et al., showed that it was possible for subjects to comply with a behavior modification for up to 6 years, with good outcomes even after a 12-year follow-up.
Lifestyle interventions in the form of diet and physical activity for up to 6 years significantly reduced the development of diabetes. The effects of diet or exercise were similar, i.e. both reduced the risk of diabetes.
In general, lifestyle interventions were equally effective irrespective of age or Gender.
They were more advantageous in older people with a lower body mass index, compared with younger persons and those with higher body mass index.
Of major interest were the findings that both lifestyle intervention and metformin were similarly effective in restoring fasting glucose, but lifestyle intervention was more effective in restoring post-load glucose values.
STOP-NIDDM study, acarbose was evaluated in a placebo controlled trial in subjects with IGT.27 After a mean follow-up of 3.3 years, the absolute risk reduction was 9 percent in acarbose group and relative risk was reduced by 36 percent when diabetes was confirmed with a second OGTT.
The results of the XENDOS trial have been published, in which orlistat and lifestyle intervention reduced risk of diabetes by 37 per cent compared with lifestyle alone.
pharmacological interventions may appear to be a more attractive option for preventing diabetes. However, lifestyle interventions have the potential to impact multiple disease states.
Diabetes prevention is a major public health issue in populations with high prevalence of type 2 diabetes, such as Asian Indians, as the rates of diabetes are projected to double over the next 20 years.
It remains for the health policymakers to make this a public health issue and urgent intervention trials are needed in these populations.
\The results of the Diabetes Prevention Trial in the Indian population are currently underway and we await the results with eagerness. However, lifestyle interventions in different racial groups may be particularly challenging,
when intervening with lifestyle measures, different strategies may need to be adopted in different racial groups.
In a study reported from Tanzania in people of Hindu religion, simple dietary advice to eat less and exercise more in the form of walking for 30 min per day, resulted in protection from progression to diabetes
In most studies of lifestyle interventions, there was a tendency towards a reduction in risk factors for cardiovascular disease such as total and LDL cholesterol and triglyceride and a decrease in systolic and diastolic blood pressure.
A high priority is not only to prevent or delay the onset of diabetes, but to reduce the future risk of macrovascular disease as well so that excess morbidity and mortality from manifestations of cardiovascular disease can be reduced.
There would appear to be a greater urgency to develop strategies to prevent type 2 diabetes, given that diabetes seems to be appearing at a younger and younger age and in some countries in children and adolescents.
On the other hand, for the results of clinical trials to prevent diabetes to be meaningful, the results need to be generalizable, but the methods need to be affordable, practical and acceptable so that these can be easily implemented.
the following conclusions and recommendations may seem logical: Increase physical activity in the population at large by low-cost, low-key, but effective interventions (population approach).
More intensive intervention should be aimed at those at high risk and a strategy is needed to identify these individuals (high risk approach).
Those who are at high risk may need to be categorized in terms of their preference and ability to comply with various interventions so that intervention can be targeted.
This may be crucial for the cost-effective utilization of resources, as some people may not choose to or be able to increase physical activity and therefore, may rely predominantly on dietary and/or pharmacological manipulations.
In a given population both approaches will be required to complement each other, as interventions in high-risk people are more likely to be successful if all the population is geared to some sort of low-key interventions.
However, this would need a clear and effective strategy to identify those at high risk by easy and effective means to target intervention.
Dinesh Nagi
Mostly excerpted from
Exercise and Prevention of Type 2 Diabetes
Due to considerable expense associated with complications of type 2 diabetes.2 Primary prevention of type 2 diabetes is, therefore, of particular interest to health economists as it has in-built secondary and tertiary prevention of complications related to diabetes.
let us look at
recently published randomized trials, which have used lifestyle intervention, including physical activity, to reduce or prevent type 2 diabetes.
However, we must remember that these studies were performed in subjects at high risk of future diabetes and not in those with normal glucose tolerance.
Therefore findings of these trials may not be applicable to the population at large.
Therefore, in any community-based or public health approach to prevent diabetes and related diseases such as coronary heart disease, this is important for effective utilization of resources.
Type 2 diabetes has a number of disease characteristics which make it potentially a preventable disease.
Considerable knowledge exists about risk factors for diabetes which are potentially modifiable
Although there is a strong genetic predisposition to this disease, environmental factors play an important role in the development of clinical diabetes.
It is also clear that both insulin resistance and defective insulin secretion contribute to the development of diabetes,
Although the relative contribution of each of these two components varies in different populations and individuals within a population.
In most subjects predisposed to develop type 2 diabetes, there is generally a long but variable period during which minor degree of glucose intolerance exists
This stage of pre-diabetes can be recognized by performing an oral glucose tolerance test and is known as impaired glucose tolerance (IGT).
It can also be diagnosed by measuring fasting plasma glucose, known as impaired fasting glucose (IFG).
Subjects thus identified are at a higher risk of future diabetes compared with those whose glucose tolerance is normal.
Identification of subjects at high risk of diabetes provides us with an opportunity to modify the disease process, either to delay or prevent it from becoming clinically manifest. As in type 2 diabetes, insulin resistance and defective insulin secretion contribute to the development of IGT and IFG.
Both of these defects can be modified through lifestyle interventions and/or pharmacological therapies.
In spite of this, it has only recently been shown that type 2 diabetes can be prevented.
Behaviour modification through diet and exercise are attractive and have the added advantage of modifying other associated conditions such as coronary artery disease, hypertension, and obesity.
However, lifestyle modifications are extremely difficult to sustain over the lifetime of a given individual.
In addition, it is likely that different strategies may need to be adopted in different ethnic groups to improve adherence to measures which will promote healthy lifestyles.
It has been known for some time that physical inactivity is associated with increased risk of type 2 diabetes.
The results of various epidemiological and observational studies showed that regular physical activity had a protective effect on the development of type 2 diabetes.
These studies were remarkable for their consistent findings in the protective effects of physical activity on the occurrence of type 2 diabetes.
In addition, some of the studies also showed a dose-response relationship between the frequency of physical activity and the degree of protective effect.
These studies suggested a causative role for physical inactivity in type 2 diabetes.
the incidence of diabetes was negatively related to the frequency of exercise
. The age-adjusted risk of diabetes in men who exercised at least once a week was 0.64 compared to those who exercised less frequently.
The protective effect of exercise was unrelated to baseline body mass index (BMI) and was more marked in obese subjects.
leisure time physical activity, expressed as the number of calories expended was found to be inversely related to the development of diabetes.
The age-adjusted risk of diabetes was 6 percent lower for each 500 kcal expended.
These beneficial effects of exercise remained significant when adjusted for the confounding effects of obesity, blood pressure and parental history of diabetes.
women who participated in a vigorous physical activity at least once a week had a 33 percent lower risk of diabetes compared with those who did not take part in such activities.
in both men and women in the highest quintile of physical activity, the risk of diabetes was approximately half compared with the rest.
self-reported moderate intensity exercise undertaken for 40 min per week was associated with 56 percent lower risk of type 2 diabetes.
They also found that high levels of cardiorespiratory physical fitness (O2 consumption in a respiratory chamber) also had a protective effect on the development of diabetes.
In subjects who were at high risk of diabetes, with even a moderate degree of physical activity taken once a week for more than 40 min, the risk of diabetes was 64 percent lower than those who did not take part in physical activity.
The major concern in the use of lifestyle intervention to prevent diabetes has been around the issue of long-term sustainability of this intervention.
The study by Eriksson et al., showed that it was possible for subjects to comply with a behavior modification for up to 6 years, with good outcomes even after a 12-year follow-up.
Lifestyle interventions in the form of diet and physical activity for up to 6 years significantly reduced the development of diabetes. The effects of diet or exercise were similar, i.e. both reduced the risk of diabetes.
In general, lifestyle interventions were equally effective irrespective of age or Gender.
They were more advantageous in older people with a lower body mass index, compared with younger persons and those with higher body mass index.
Of major interest were the findings that both lifestyle intervention and metformin were similarly effective in restoring fasting glucose, but lifestyle intervention was more effective in restoring post-load glucose values.
STOP-NIDDM study, acarbose was evaluated in a placebo controlled trial in subjects with IGT.27 After a mean follow-up of 3.3 years, the absolute risk reduction was 9 percent in acarbose group and relative risk was reduced by 36 percent when diabetes was confirmed with a second OGTT.
The results of the XENDOS trial have been published, in which orlistat and lifestyle intervention reduced risk of diabetes by 37 per cent compared with lifestyle alone.
pharmacological interventions may appear to be a more attractive option for preventing diabetes. However, lifestyle interventions have the potential to impact multiple disease states.
Diabetes prevention is a major public health issue in populations with high prevalence of type 2 diabetes, such as Asian Indians, as the rates of diabetes are projected to double over the next 20 years.
It remains for the health policymakers to make this a public health issue and urgent intervention trials are needed in these populations.
\The results of the Diabetes Prevention Trial in the Indian population are currently underway and we await the results with eagerness. However, lifestyle interventions in different racial groups may be particularly challenging,
when intervening with lifestyle measures, different strategies may need to be adopted in different racial groups.
In a study reported from Tanzania in people of Hindu religion, simple dietary advice to eat less and exercise more in the form of walking for 30 min per day, resulted in protection from progression to diabetes
In most studies of lifestyle interventions, there was a tendency towards a reduction in risk factors for cardiovascular disease such as total and LDL cholesterol and triglyceride and a decrease in systolic and diastolic blood pressure.
A high priority is not only to prevent or delay the onset of diabetes, but to reduce the future risk of macrovascular disease as well so that excess morbidity and mortality from manifestations of cardiovascular disease can be reduced.
There would appear to be a greater urgency to develop strategies to prevent type 2 diabetes, given that diabetes seems to be appearing at a younger and younger age and in some countries in children and adolescents.
On the other hand, for the results of clinical trials to prevent diabetes to be meaningful, the results need to be generalizable, but the methods need to be affordable, practical and acceptable so that these can be easily implemented.
the following conclusions and recommendations may seem logical: Increase physical activity in the population at large by low-cost, low-key, but effective interventions (population approach).
More intensive intervention should be aimed at those at high risk and a strategy is needed to identify these individuals (high risk approach).
Those who are at high risk may need to be categorized in terms of their preference and ability to comply with various interventions so that intervention can be targeted.
This may be crucial for the cost-effective utilization of resources, as some people may not choose to or be able to increase physical activity and therefore, may rely predominantly on dietary and/or pharmacological manipulations.
In a given population both approaches will be required to complement each other, as interventions in high-risk people are more likely to be successful if all the population is geared to some sort of low-key interventions.
However, this would need a clear and effective strategy to identify those at high risk by easy and effective means to target intervention.
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