Dyslipidemia in type 2 diabetes
mellitus – a major risk factor for cardiovascular morbidity
Bobby D 1, Vinodha R 2
1Dr. Bobby. D, Assistant Professor, Department of Physiology,
Government Villupuram Medical College, Villupuram, Dr MGR University,
India, 2Dr. Vinodha. R, Professor and Head of the Department,
Department of Physiology, Thanjavur Medical College, Thanjavur, Dr MGR
University, India
Address for
Correspondence: Dr. Bobby. D, Assistant Professor,
Department of Physiology, Government Villupuram Medical College, Dr MGR
University. email id- bobbyraja26@yahoo.com
Abstract
Introduction:
Diabetes mellitus is growing worldwide like an epidemic. Early
identification of cardiovascular risk factors will decrease the
morbidity in type 2 diabetes mellitus. This study was done to assess
the prevalence of dyslipidemia among type 2 diabetic population. Methods: 40 cases of
type 2 DM with duration of 8 to 12 yrs and 40 controls of both males
and females in the age group of 40 to 65yrs were selected. Laboratory
investigations like fasting glucose and lipid profile (fasting) were
taken. Results:
In the present study the levels of fasting glucose, total cholesterol,
low density lipoproteins, triglycerides were high and the levels of
high density lipoproteins were low in the type 2 diabetics compared to
controls. Conclusion:
Thus this study suggests the importance of early detection of
dyslipidemia in type 2 diabetics mellitus and will reduce the
prevalence of complications in diabetics.
Keywords:
Type 2 diabetes mellitus, Cardiovascular risk factor, Dyslipidemia
Manuscript received:
20th June 2016, Reviewed:
4th July 2016
Author Corrected:
14th July 2016, Accepted
for Publication: 28th July 2016
Introduction
Diabetes mellitus is a syndrome of chronic hyperglycemia due to insulin
deficiency, resistance or both. Two types of diabetes mellitus have
been described. Type I is caused by T- cell mediated autoimmune
destruction of islet insulin secreting beta cells. Type II is
characterized by the resistance to insulin with both hyperglycemia and
hyperinsulinemia followed by the deficiency of insulin [1]. Type II
diabetes is associated with two to four fold increase in the risk of
cardiovascular disease. Cardiovascular diseases are the main cause of
morbidity and mortality among type II diabetic patients and an
estimated 75% to 85% of diabetes die because of cardiovascular
diseases. This occurs as a result of atherosclerotic progress in
diabetes. Type 2 diabetes is frequently associated with cardiovascular
risk factors (CVRF) such as hypertension and dyslipidemia and that the
prevalence of other factors such as smoking , sedentary
lifestyle and obesity is greater than in
non diabetic population. The global prevalence of diabetes in
2010 is 6.6% (285 million) and it is expected to increase to 7.8% (438
millions) in 2030. In addition, there are 344 million people with IGT
(impaired glucose tolerance) in 2010 which is predicted to rise to 472
million by 2030. Unfortunately, India tops the list with the largest
number of diabetics (57 millions in 2010) which is expected to rise to
90 millions in another 20 years. The high prevalence is due to strong
genetic predisposition, and also by the presence of low threshold
levels for age and environmental risk factors for diabetes [2].
Dyslipidemia is an important contributing factor to the cardiovascular
complication in diabetes mellitus. Lipid disturbances in diabetes
mellitus are dominated by hypertriglyceridemia, and low High density
lipoprotein cholesterol (HDL-C). Although average Low density
cholesterol (LDL-C) levels may not be increased, diabetic patients have
higher concentrations of small dense LDL-C. These proatherogenic
particles are readily oxidised and taken up by monocytes and
endothelial smooth muscles, contributing to atherogenesis and
subsequent progression of atherosclerosis [3].
Materials
and Methods
This study was undertaken to assess the cardiovascular risk factors in
type 2 DM. Case control type of study was done. The study was approved
by Ethical committee of Thanjavur Medical College. The study was
conducted during 2009-2011. 40 cases of type II DM, 8-12 yrs duration,
40 to 65yrs both male and female were selected from patients
attending diabetic OP at Thanjavur medical college. Age and sex matched
controls were selected from the healthy, non-diabetic general
population residing at Thanjavur district.
Informed consent was obtained from all subjects prior to enrolment into
the study. A proforma with detailed history of the subjects
were filled. Height, weight, BMI were measured. General examination was
done including examination of CVS, RS, CNS and abdomen. Vital signs
were recorded. Baseline investigations were done for all subjects,
including Fasting Blood Sugar, haemoglobin estimation, ECG.
Biochemical analysis-
Collection of blood samples for biochemical assay was done after
fasting for at least 12 hrs. Blood samples were collected in the
morning. 5 ml of blood from antecubital vein from each subject was
collected aseptically in disposable sterile 5 ml syringe and was
allowed to clot. Samples were processed within 1hour for quantitative
lipoprotein cholesterol measurements using the vertical spin
centrifugation technique –serum was obtained by
centrifugation for 4 mins at 3000 rpm and was transferred into properly
labelled sterile vials stored at -20 ºC till the performance
of lipid profile. Serum total cholesterol, triglycerides, High density
lipoprotein tests were evaluated by standard enzymatic kits methods
whereas low density lipoprotein was calculated according to FRIEDWALD
FORMULA LDL = Total cholesterol – { (TGL/5) + HDL}
(If TGL IS < 400mg /dl). Total cholesterol was estimated using
CHOD-PAP method enzymatic assay. Serum triglyceride was estimated
employing standard GPO-POD method of enzymatic assay. HDL cholesterol
was estimated by PEG precipitation method. These test were carried out
in a semi autoanalyzer.
Statistical analysis was done using Epidemiological Information package
(EPI2010) developed by Centre of Disease Control, Atlanta. All data
were compared between the diabetic and the control groups using the
software, frequencies, percentages, mean, standard deviations were
calculated. Chi-square test was used to test the significance of
difference between variables. A 'p' value less than 0.05 is taken to
denote significant relationship.
Results
As seen in table 1 the mean serum cholesterol in diabetics is 229
± 39.5 mg/dl and the mean cholesterol in controls is 192
± 33.5 mg/dl. The values of total cholesterol are
significantly higher in diabetics than in non diabetics. The P value is
< 0.0001. The mean serum triglycerides in diabetics is 216
± 74.25 mg/dl and the mean value in non diabetics is 157
± 385 mg/dl. The values of serum triglycerides are
significantly higher in diabetics than in control group. The P value is
< 0 .0001. The mean serum HDL in diabetics is 38.9±
55 mg/dl and the mean for non diabetics is 44.8± 5.55 mg/dl.
The values of HDL are found to be lower in diabetic than in non
diabetic. The P value is < 0 .0001. The mean serum LDL
cholesterol in diabetics is 147 ± 41.5 mg/dl and the mean
for non diabetic is 116.1± 32.75 mg/dl. The values of serum
LDL are significantly higher in diabetic than in control. The P value
is < 0 .0003.
Table-1: Observation of
all Parameters
|
Parameters
|
N
|
Minimum
|
Maximum
|
Mean
|
Standard deviation
|
|
AGE (yrs)
|
80
|
39
|
70
|
58
|
8.4
|
|
Total Cholesterol
|
|
|
|
|
|
|
mg/dl
|
80
|
155
|
310
|
229.2
|
39.5
|
|
TGL mg/dl
|
80
|
109
|
390
|
216.4
|
74.2
|
|
HDL mg/dl
|
80
|
34
|
51
|
38.9
|
5.0
|
|
LDL mg/dl
|
80
|
49.4
|
242.2
|
147
|
41.5
|
Table-2: Observation
about total cholesterol in this study
|
Group
|
No. of cases
|
Total Cholesterol
|
|
<200mg/dl
|
>200mg/dl
|
|
N
|
%
|
N
|
%
|
|
Diabetic
|
40
|
11
|
27.5
|
29
|
72.5
|
|
Control
|
40
|
31
|
77.5
|
9
|
22.5
|
|
P
|
<.0001
|
77.5% of controls have serum total cholesterol value < 200 mg/dl
and 22.5% have serum total cholesterol > 200 mg/dl. In
study group 27.5 % show serum Total cholesterol < 200 mg/dl and
72.5% show serum total cholesterol > 200 mg/dl. The
result shows that most of the diabetics have raised values of serum
total cholesterol compared to non diabetics.
Table-3: Triglycerides in
this study
|
Group
|
No.of cases
|
Triglyceride
|
|
<150 mg/dl
|
>150 mg/dl
|
|
N
|
%
|
N
|
%
|
|
Diabetic
|
40
|
5
|
12.5
|
35
|
87.5
|
|
Control
|
40
|
29
|
72.5
|
11
|
27.5
|
|
P
|
<.0001
|
In the control group 72.5% show serum triglyceride <150 mg/dl
and 27.5% of them show a value >150 mg/dl. In diabetic
group 12.5 % show serum triglyceride <150mg/dl and 87.5% show
serum triglyceride value >150 mg/dl. So the result shows that
there is a definite increase in triglyceride in diabetics than control
groups.
Table-4: Observation
about HDL cholesterol
|
Group
|
No. of cases
|
High Density
Lipoprotein
|
|
<40 mg/dl
|
>40 mg/dl
|
|
N
|
%
|
N
|
%
|
|
Diabetic
|
40
|
32
|
80
|
8
|
20
|
|
Control
|
40
|
8
|
20
|
32
|
80
|
|
P
|
<.0001
|
Among non diabetics 20% of them have HDL values <40 mg/dl
whereas 80 % of them have > 40 mg/dl. Among diabetic 80% of them
have serum HDL values <40 mg/dl and 20% shows HDL value >
40 mg/dl. The results show reduced serum HDL values in diabetics when
compared with controls.
Table-5: Observation
about LDL cholesterol
|
Group
|
No.of cases
|
Low Density Lipoprotien
|
|
<130 mg/dl.
|
>130 mg/dl.
|
|
N
|
%
|
N
|
%
|
|
Diabetic
|
40
|
15
|
37.5
|
25
|
62.5
|
|
Control
|
40
|
31
|
77.5
|
9
|
22.5
|
|
P
|
<.0001
|
77.5% of controls show serum LDL <130 mg/dl and 27.5% of them
show >130 mg/dl. In the study group 37.5 % of diabetic
show serum LDL <130mg/dl and 62.5% show serum LDL value
>130 mg/dl. The result show that there is a
definite increase in LDL in diabetics than control groups.
Table-6: Observation
about Dyslipidemia
|
Group
|
No.of cases
|
Dyslipidemia
|
|
Present
|
Absent
|
|
N
|
%
|
N
|
%
|
|
Diabetic
|
40
|
35
|
87.5
|
5
|
12.5
|
|
Control
|
40
|
14
|
35
|
26
|
65
|
|
P
|
<.0001
|
In controls 35% have dyslipidemia and 65% have normal lipid level. In
the study group (diabetics) 87.5% show dyslipidemia and 12.5% have
normal lipid level. The results show that most of the
diabetics have raised lipid levels than controls.
Discussion
The incidence of myocardial infarction, stroke is increased
two to three fold in diabetes mellitus patients and the risk of death
is increased two to three fold independent of other known risk factors
for cardiovascular disease. In the present study the results indicate
that subjects with diabetes mellitus of 8 to 12 years duration show a
significant change in lipid profile compared to controls.
Serum Total
Cholesterol- Significant difference was observed
between diabetic and control group in total cholesterol values. The
mean ± SD of serum total cholesterol in control is 192.3
± 33.5mg/dl, while it is significantly higher in diabetics,(
229 .2 ± 39.5 mg/dl. P = 0.0001). Results found by Guanmin
chen et al( 2011) supports the findings of our study[4].
Sharon H Saydah et al (2004) in a study of diabetics with
cardiovascular disease also found a significant rise in serum
cholesterol in diabetics(222.8 mg/dl)[5]. Andan Gokcel et al
(2001) have found a similar rise in serum cholesterol in
their study. They used only female subjects for study, while both sexes
have been included in my study [6].
Serum Triglycerides- Significant
difference was observed between diabetics and control. The mean
± SD of triglycerides level in diabetics and control is
216.4±74.2mg/dl and 157±38 mg/dl respectively (P
= 0.0001). The results are comparable to the following
studies:
Steven. M. Haffner et al (1998) in a cross sectional study between
diabetics and non diabetics showed significant rise in serum
triglycerides 223 mg/dl[7]. R.C. Turner et al (1998) also
found a significant rise of serum triglycerides in diabetics which is
similar to the present study[8]. Herman. A. Taylor et al ( 2009) have
done a study in African –Americans (Jackson Heart study
participants). They found statistically significant rise in serum
triglycerides in their study [9].
HDL Cholesterol- The
Mean ± SD serum HDL in diabetic group is 38.9 ± 5
mg/dl compared with higher value in control group (44.8 ±5.5
mg/dl). This difference was statistically significant (P
=0.0001). These observations are similar to other studies.
Anthony keech et al ( 2003) in their study in diabetics, prediabetics
and normal subjects found significant decrease in HDL levels, as seen
in the present study[10]. Elizabeth Selvin et al (2005) have done a
study in African – Americans (The atherosclerosis risk in
community study). They have found significant decrease in HDL which is
in conformity with my study[11]. James.R.Gavin ( 2008) has also found a
significant decrease in HDL in diabetics in his study[12].
LDL Cholesterol- The
mean ± SD serum LDL in diabetics is 147 ± 41.5
mg/dl compared to 116 ± 32.7 mg/dl in the controls. This
difference is statistically significant.(P = 0.0003)
Salvador Trenche et al (2005) have found significantly raised serum LDL
in a study in diabetics including newly diagnosed diabetes
(158±72.9mg/dl ) which is similar to my study[2]. H.Surekha
rani et al (2005) have done a study in people with type 2 DM and found
a significant rise in serum LDL (135.56±32.57mg/dl).
RC.Turner et al (1998) found a significant rise in serum LDL. These
results are similar to my study [13].
Conclusion
The present study found significant increase in levels of serum total
cholesterol, triglycerides, low density lipoproteins, and significant
decrease in levels of high density lipoprotein in subjects with Type 2
diabetes mellitus. The estimation of lipid profiles in diabetes
mellitus in early stage is very useful to assess the cardiovascular
risk and will help the patient to improve and reduce the morbidity and
mortality. This will go a long way in decreasing health costs incurred
due to cardiovascular complications of diabetes and will help to
improve the quality of life.
Acnowledgement-We
thank the Dean, Thanjavur Medical College for giving us full support
during all stages of the study.
Funding:
Nil, Conflict of
interest: None initiated
Permission from IRB:
Yes
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How to cite this article?
Bobby D, Vinodha R. Dyslipidemia in type 2 diabetes mellitus
– a major risk factor for cardiovascular morbidity. Int J Med
Res Rev 2016;4(8):1387-1391.doi:10.17511/ijmrr.2016.i08.17.