Consequences of Physical Activity on the Markers of Glycemic Status among Type 2 Diabetic Subjects

 

R. Suja Pandian¹* and M. Ramalingam²

¹Department of Biochemistry, PRIST University, Thanjavur

²Center for Research and Development, PRIST University, Thanjavur

^*Corresponding Author E-mail: sruthivelan@gmail.com

 

ABSTRACT:

Diabetes is a chronic disease increasing in explosive pattern in India and Thanjavur is not an exception to it. Changes in socio-economic pattern and life styles may be important in addition to susceptible genes for the causation. Our studies are intended to find out the consequences of physical activity (walking) on the markers of glycemic status among diabetic subjects residing in Thanjavur town. Male subjects with the age groups 35-45, 46-55, and 56-65 years were selected and categorized as young, middle and old aged diabetic subjects. All the human volunteers were issued with a questionnaire to determine the eligibility for participation in the study. BMI was used as measure of relative body weight and was calculated as the weight in kilograms divided by the height in meters squared by the method as given by WHO 1995. The blood was collected by venous arm puncture in heparinized and unheparinized tubes after an overnight fasting for the separation of plasma and serum. The levels of fasting blood glucose (FBG) and the levels of BMI were significantly elevated among the middle and old age diabetic subjects, when compared with the normal subjects. However the level of FBG and BMI was found to be significantly low to near to normal levels, among the different age groups of physically active diabetic subjects. Older diabetic subjects were found to have a low level of fasting insulin compared to other age groups. Physically active diabetic subjects showed no significant variation in their insulin levels among the different age groups. It is evident that FBG is positively and significantly correlated (P<0.01) with HbA1C and BMI. But, it is negatively and significantly correlated (P<0.01) with fasting insulin.  Fasting insulin is shown to be negatively and significantly correlated (P<0.01) with the FBG, HbA1C and BMI.

 

 

1. INTRODUCTION:

India has the dubious distinction of having the highest prevalence of diabetes worldwide. Diabetes is increasing in an alarming proportion especially in South East Asia¹. Diabetes is a chronic disease increasing in explosive pattern in India and Thanjavur is not an exception to it. Changes in socio-economic pattern and life styles may be important in addition to susceptible genes for the causation ².

 

Diabetes is rightly labeled as a lifestyle disease, but it doesn't imply that the poor and underserved communities are not at risk of diabetes. Simple, daily, vigorous walking can significantly improve cardiac risk factors and glucose metabolism. Because walking is accessible and relatively safe and can be easily incorporated into daily routines, it is a form of exercise that is practical and suitable for most diabetic patients, especially elderly persons.

 

Nevertheless, optimal planning and precautions are needed in any exercise program for diabetic patients so that exercise-induced hypoglycemia and other complications can be minimized.

 

Diabetes mellitus, a complex metabolic disorder is characterized by failure to properly utilize glucose and other metabolites in the body causing spill over of these substances in the urine, mainly due to relative or absolute deficiency of insulin secretion by the beta cells of pancreas. This diabetes stage can be identified by using markers of glycemic control such as fasting blood glucose (FBG) level, Glycated Hemoglobin (HbA₁C), Body Mass Index (BMI) and insulin which are the bench mark to know the extent of damage caused to the patients in their life. Our studies are intended to find out the consequences of physical activity (walking) on the markers of glycemic status among diabetic subjects residing in Thanjavur town.

 

 

MATERIALS AND METHODS:

Study population

For the present study, only the male subjects were selected. The age groups selected were 35-45, 46-55 and 56-65 years and categorized as young, middle and old aged diabetic subjects. All the human volunteers were issued with a questionnaire to determine the eligibility for participation in the study. The questions elicited vital information on age, body weight, height, exercise, habits, health status, smoking habit, alcohol intake and the use of dietary supplements. Physically active diabetic subjects with the habit of walking for at least 30 min / day or 2 days once were included for the investigation. Written informed consent was obtained from all the participants of the study after providing sufficient explanation for participation in the study.

 

Anthropometric Measurements

Body weight and height were measured while the subjects were wearing light indoor clothing and without shoes. BMI was used as measure of relative body weight, and was calculated as the weight in kilograms divided by the height in meters squared by the method as given by WHO 1995.

 

Collection of Samples

The blood sample was collected from the subjects chosen for the study using the method described by NCCLS³. The blood was collected by venous arm puncture in heparinized and unheparinized tubes after an overnight fasting. Plasma and serum were separated by centrifugation at 1300 x g for 15 min and stored at 4°C until analysis for FBG, HbA₁C and fasting insulin.

 

RESULTS:

The level of FBG in the normal, diabetic subjects and physically active diabetic subjects are depicted in Table 1. The control group showed the lowest FBG level     (85.60 ± 13.36). Further, it can be inferred from the table that the levels of FBG was significantly elevated (P<0.01) among the middle and old age diabetic subjects, when compared with the normal subjects. However the level of FBG was found to be significantly low to near to normal levels, among the different age groups of physically active diabetic subjects.

 

From the table 2 it is shown that the levels of HbA1C to be normal in the control (3.6 ± 0.4) and higher in the older diabetic subjects.

 

Table-1. Effect of walking on fasting blood glucose levels among young middle and old aged diabetic subjects

Values are expressed as means±SD

Table- 2. Effect of walking on glycated haemoglobin levels among young, middle and old aged diabetic subjects

Values are expressed as means±SD

 

 

 

The analysis of variance showed significantly increased level of HbA1C in diabetic subjects, compared to normal subjects. Lifestyle intervention with the habit of walking is depicted to reduce the levels of HbA1C (P<0.01) to near normal among the diabetic subjects.

 

The levels of BMI of normal and the diabetic subjects are depicted in Table 3. It can be noticed from the table that the levels of BMI was significantly high in the middle and old aged diabetic subjects. Physically active diabetic subjects showed a significantly lower F value (18.98) among different age groups of diabetic subjects.

 

The mean values of insulin among the different age groups of diabetic subjects are indicated in Table 4. It can be seen from the table that the level of insulin is significantly different in all the age groups of different groups. Older diabetic subjects were found to have a low level of fasting insulin compared to other age groups. Physically active diabetic subjects showed no significant variation in their insulin levels among the different age groups.

 

 

Table-3. Effect of life style interventions on BMI levels among young middle and old aged diabetic subjects

Values are expressed as means±SD

 

Table-4. Effect of life style interventions on fasting insulin levels among young middle and old aged diabetic subjects

Values are expressed as means±SD

Table 5 shows the correlation analysis of the relationship between the markers of glycemic control among diabetic subjects. It is evident that FBG is positively and significantly correlated (P<0.01) with HbA₁C and BMI. But, it is negatively and significantly correlated (P<0.01) with fasting insulin.  Fasting insulin is shown to be negatively and significantly correlated (P<0.01) with the FBG, HbA₁C and BMI.

 

Table-5. Correlation between the markers of glycemic control among diabetic subjects with different lifestyle interventions

** Correlation is significant at the 0.01 level

* Correlation is significant at the 0.05 level

 

DISCUSSION:

Diabetes mellitus may be defined as a heterogeneous group of metabolic disease characterized by hyperglycemia resulting from defects in insulin secretion or insulin action or both. A long duration of metabolic disturbances due to insufficient insulin secretion can cause vascular damage leading to both macrovascular and microvascular complications⁴. In the present study it has been observed that the old aged people recorded high FBG values than the younger and middle aged groups. It may be suggested that during the natural process of aging insulin action is impaired and enhanced oxidative stress occur. It is also known that oxidative stress may impact the function of many enzymes involved in glucose metabolism. It has been demonstrated that an age dependent rise in oxidative stress is associated with a significant decline in whole body glucose disposal and non oxidative glucose metabolism.

 

Enhanced free radical production can move a hydrogen atom to another polyunsaturated fatty acid, thus generating another lipid free radical and lipohydroperoxide. This latter event produces damage in living cells through at least two mechanisms 1) mechanical disruption of membranes, causing a loss of the coordinated function of enzymatic systems contained in them and 2) production of toxic substances from the disintegration of polyunsaturated fatty acids, which are then able to migrate from the production site and reach a distant target⁵.

 

Further, in the present study the physically active diabetic subjects showed near normal levels of FBG levels. Physical activity may reduce the risk of T2DM, by increasing glucose disposal through a number of pathways. Physical activity has independent effects on glucose disposal by increasing both insulin mediated and non insulin mediated glucose disposal⁶. The increased insulin sensitivity occurs because of increase in the number and activity of glucose transporters (especially the GLUT4 isoform) both in muscle and adipose tissue⁷. Glycogen synthase activity is also increased which results in increased glycogen synthesis and non oxidative disposal of glucose ⁸.

 

Sato et al. ⁹ reported that the level of HbA₁C is a reliable index of glycemic control in diabetes. HbA₁C is commonly considered to reflect the previous 8-12 weeks average blood glucose concentration. Several studies done earlier in diabetic subjects showed the contribution of FBG to HbA₁C. Inouye et al. ¹⁰ reported that during diabetes, the excess glucose present in the blood reacts with hemoglobin to form HbA₁C. Glycation is enhanced by elevated glucose levels inducing the formation of oxygen derived free radicals.

 

Sato et al. ⁹ suggested the use of combined measurement of FBG and HbA₁C to predict T2DM. However the present study showed that the above mentioned glycemic index are considerably reduced and positively correlated with physically active group. This proved that lifestyle intervention had a positive impact in controlling diabetes. Fowler ¹¹ suggested that glycemic control is fundamental in the management of diabetes. Physical activity is shown to reduce the levels of HbA₁C to below or around 7% reducing microvascular and neuropathic complication of T2DM. Cadd¹² proved that exercise therapy greatly benefit many patients with diabetes by reducing hyperglycemia, insulin resistance, dyslipidemia and hypertension. Exercise aid in weight loss, specifically loss of fat and also improve glycemic control in people with diabetes. Additionally, exercise improves physical function and quality of life in people with diabetes. It may be suggested that daily walking not only reduces body weight but also improves insulin sensitivity among diabetic subjects.

 

In the present study the BMI was found to be more in the middle and old age groups compared to other groups. Low BMI was noticed in the control group and who are physically active. The level of fasting insulin was low in the older diabetic group compared to other age groups. This may be attributed to less physical activity among old people and poor diabetic control which might have affected pancreas resulting to low levels of insulin.

 

In the present study the Group having the habit of regular walking showed an optimum level of FBG, HbA1C, BMI and insulin. This was found to be almost similar to the value of control group. Regular exercise showed to improve blood glucose control and reduce cardiovascular risk factors contributing to weight loss and improve well being¹³. Smith and Zachwieja¹⁴ reported that physical activity facilitates weight loss and weight maintenance. Individuals expending a great deal of energy on physical activity tend to have lower adiposity. The loss of adipose tissue resulting from physical activity is often visceral rather than subcutaneous fat which is strongly associated with insulin resistance and the related metabolic syndrome.

 

Diabetes mellitus has become one of the great epidemics of our time, affecting nearly 150 million adults worldwide. Elderly diabetic subjects have shown to have a significant increase in the markers of glycemic control. It has been demonstrated that an age dependent rise in oxidative stress is associated with a significant decline in whole body glucose disposal and non oxidative glucose metabolism. As glycemic control is fundamental in the management of diabetes, physical activity greatly benefit diabetic subjects by reducing hyperglycemia, insulin resistance and also improve glycemic control in people with diabetes.

 

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Received on 18.09.2012       Modified on 09.10.2012

Accepted on 25.10.2012      © RJPT All right reserved