An Investigation of Some Biochemical Parameters Among Diabetic Adult
Chapter One
AIMS AND OBJECTIVES
GENERAL
To determine the biochemical parameters of Type 2 diabetics in the South-South zone of Nigeria and investigate any association with glycaemic control.
SPECIFIC
- To determine the biochemical parameters listed below in patients attending the Diabetic Clinic in University of Uyo Teaching These are:
- Protein C antigen levels
- Prothrombin time
- Activated partial thromboplastin time
- Platelet count
- To compare protein C levels between Type 2 diabetics and normal
- To assess the degree to which glycaemic control affects their biochemical parameters.
- To determine the factors associated with reduced protein C levels among Type 2 diabetic
Chapter Two
LITERATURE REVIEW
Diabetes is associated with reduced life expectancy and reduced quality of life. Chronic hyperglycaemia is associated with long term consequences which include dysfunction and damage to the nerves, eyes, kidneys and cardiovascular system33. Diabetic complications are either microvascular (nephropathy, retinopathy, neuropathy) or macrovascular (stroke, peripheral vascular disease, ischaemic heart disease)33.
In 2011, forty-six million deaths globally were attributed to diabetes mellitus alone6 and thrombotic events result in 80% of diabetic deaths24,30. These thrombotic events are due to the hypercoagulable state that characterizes diabetes mellitus and the associated hypofibrinolysis which worsens it 25,26,27. Disturbances of the haemostatic system that contribute to this hypercoagulable state have been described in various studies carried out over time in different populations26,28-32. Hyperglycaemia has been linked with increased risk of thrombosis due to activation of coagulation in both healthy and diabetic populations, while merely reducing the blood sugar levels actually reduced the risk of thrombosis 34-37.
Hyperglycaemia causes tissue damage by acute reversible changes in cellular metabolism and cumulative, irreversible changes in macromolecules. This damage occurs all over the body producing the different manifestations seen in the micro- and macro-vascular complications associated with DM. The pathways associated with diabetic complications in different organ systems are interrelated and discussed below.
Chronic hyperglycaemia, has been shown to be the critical initiating factor for all types of micro-vascular disease in DM 38,39. In general, all diabetic cells are exposed to high levels of plasma glucose but hyperglycaemic damage is limited to cell types e.g. endothelial cells that are unable to down regulate glucose transport into the cell leading to intracellular hyperglycaemia 38,39. These vascular cells that directly encounter hyperglycaemia are the ones that show the earliest pathologic responses 40.
The pathways through which hyperglycaemia causes damage to endothelial cells are inter-related and are discussed below.
The Polyol Pathway:
Aldose reductase catalyses the Nicotinamide Adenine Diphosphate (NADPH)- dependent reduction of carbonyl containing compounds like glucose. Chronic hyperglycaemia leads to an increase in intracellular glucose which is converted to sorbitol and sorbitol dehydrogenase oxidizes it to fructose. At this point NAD+ is reduced to NADH. When sorbitol accumulates in the cell it causes an increase in cellular osmolarity with resultant water influx which culminates in cellular oedema. When the pathway is over activated due to chronic hyperglycaemia, there is consumption of NADPH that is needed to generate reduced glutathione (GSH) which could induce oxidative stress on the long run41,42. The effects of oxidative stress are discussed below.
CHAPTER THREE
PATIENTS, MATERIALS AND METHODS
STUDY DESIGN
It was a cross sectional study.
SAMPLING TECHNIQUE
A systematic random sampling method was employed in recruiting the participants. Every third patient who came to the diabetic clinic (for subjects) and the General Out Patients Department (for control) and met the inclusion criteria was recruited into the study. In the cases of refusal of consent, the next patient was approached.
INCLUSION CRITERIA
Adults with confirmed type 2 diabetes mellitus of at least one year duration who gave informed understood consent were recruited into the study.
EXCLUSION CRITERIA
- Diabetic patients with chronic liver disease
- Diabetic patients with any form of bleeding disorder
- Diabetic patients on anticoagulation
- Women on oral contraceptive pills
- Pregnant women
- Diabetic patients with haemoglobinopathies
- Patients who did not give consent
CONTROL POPULATION
Drawn from individuals in the General Out Patients Department
CHAPTER FOUR
RESULTS
SOCIODEMOGRAPHIC CHARACTERISTICS OF PARTICIPANTS
A total of 88 people were part of this study with 44 being the subjects and 44 being the control group.
CHAPTER FIVE
DISCUSSION
Diabetes mellitus, which has been defined by the WHO as a disorder of multiple aetiologies characterized by chronic hyperglycaemia with disturbances of carbohydrate, fat and protein metabolism that result from defects in insulin secretion, insulin action or both1, has also been described as a hypercoagulable state with hypofibrinolysis 25, 26, 27 . The hypercoagulable state is as a result of the chronic hyperglycaemia causing changes in the vascular endothelium, platelets, coagulation factors, natural anticoagulants and the fibrinolytic system 25.
This study has looked at the biochemical parameters of type two diabetics attending the Diabetes Clinic of University of Uyo Teaching Hospital, Uyo and related these parameters with their glycaemic control. The aim of the study was to see if their biochemical parameters could predict their risk for thrombosis.
Studies that have been carried out in different parts of the world have given controversial values for haemostatic profiles of diabetics 26, 28, 29, 30, 31. In Nigeria, different values have also been given for some biochemical parameters 53, 65, 99, 32. Some of these studies found shortened PT and APTT intervals 61,62,63,64 while others found prolonged PT and APTT intervals 29,60,65.
Haemostatic findings
The mean platelet counts in this study of both subjects and controls did not vary significantly. Subjects had 222.16 x 109/L while controls had 216.95 x 109/L with a p value of 0.69 which makes it not statically significant. This is similar to other studies done in Nigeria 53 and other parts of the world 25. Though some studies have found significantly reduced 29,102 or increased 30,103,104 platelet counts in diabetics. Platelets tend to be hyper reactive due to increased secretion and aggregation54. This is how they increase the risk of thrombosis in diabetics.
The mean prothrombin time (PT) of subjects in this study was 13.6 seconds while control group had 15.6 seconds; p value was <0.05 which is statistically significant. The mean International Normalized ratio (INR) of the subjects was 0.97 while that of the control group was 1.04 with a statistically significant p value of <0.05. These values are however within normal limits. The normal range for INR is 0.8-1.2. This is similar to studies done in Nigeria 32, however other studies done in Nigeria showed prolonged intervals for PT 65,99. The methodologies used in carrying out the tests are factors that could account for the differences found in our local studies. The other local study with similar results was done in the south south geopolitical zone of the country 32. Similar studies carried out in other parts of the world also came up with shortened values for PT 105. The reasons for these short values could be due to an increase in prothrombin levels which have been found in type 2 diabetics 106.
The mean activated partial thromboplastin time (APTT) of subjects was slightly shorter with 34.81 seconds than that of the control group which had 35.03. The difference though was not statistically significant with a p value of 0.34. This shorter APTT value is also similar to some local99 and international61,62,63,64 studies. This finding could also be due to increased plasma prothrombin levels.106
Normal protein C antigen level is taken to be 4ug/ml with a range of 2.0 to 4.0. The protein C antigen level of the diabetic group was 4.50 ug/ml, with a range of 2.0 – 6.4 ug/ml. The control group had 4.36 ug/ml, with a range of 2.3 – 6.0 ug/ml. This difference in both groups is not statistically significant p value of
0.34. Higher protein C antigen level in diabetics was found in studies done in China 29, 91 while other studies have found reduced protein C antigen 32. In studies done globally in diabetics, the protein C antigen levels have remained controversial.
Glycaemic control
Glycated haemoglobin (HbA1c) measures the glycaemic control over 2-3 months. The HbA1c of the subjects was higher with a value of 8.22% than that of the control group which was 5.66%. This difference was statistically significant with a p value of <0.05. According to WHO, the cut off value for diabetes using HbA1c is 7.0%. In this study, the duration of illness for all the subjects was over a year. Thirty five of them (79.5%) had been diabetic for more than five years as at the time of this study. This finding of higher HbA1c is similar to studies done in Pakistan103.This finding shows that the diabetic population here has poor glycaemic control generally. Hyperglycaemia has been found to be a risk factor for thrombosis in diabetics and this finding puts the subjects in this study at risk for thrombosis. The reasons for this degree of poor glycaemic control needs to be looked into because it would help in reducing the complications associated with the condition.
Correlation of biochemical parameters with glycaemic control
When the platelet counts were related to glycaemic control, no correlation was found. Spearman’s rho was 0.10 with a p value of 0.52. This showed that glycaemic control had no effect on platelet counts. In other studies that had been done, platelet counts were reduced29, normal25,93 or increased30. A study in Benin32 showed a positive correlation of glycaemic control with platelet count.
When PT was related to glycaemic control, no correlation was found, with a p value of 0.08.
The APTT in this study did not show any correlation with glycaemic control with a p value of 0.89.
Protein C antigen levels also did not have any correlations with glycaemic control, with a p value of 0.64.
In this study, glycaemic control was found to have no effect on any of the biochemical parameters studied.
Factors associated with reduced protein C antigen levels
Factors associated with reduced protein C levels were also studied. The factor found to have a negative relationship with protein C was total WBC. With rising total WBC, protein C antigen levels were found to reduce. This was after correcting for age, sex, DM duration, SBP, DBP, BMI, PCV, WBC, Platelets, PT, APTT and HbA1c. A high WBC has been found to be a predictor for development of T2DM107 and is associated with macro- and micro- angiopathic complications of T2DM108. A high WBC which is a marker of inflammation, which is seen in sepsis, has been found in T2DM10. The finding in this study that was associated with reducing protein C levels was an increase in the total WBC. This finding of low protein C with increasing total WBC is similar to findings where there is an increase in total WBC like sepsis where protein C levels have been found to be reduced109. Studies have found that activated
protein C (APC) is reduced in sepsis. Protein C is converted to APC which acts in sepsis to limit inflammatory response by inhibiting the continued production of pro-inflammatory cytokines110 and also interferes with monocytes and neutrophil migration to sites of inflammation, in this way it further limits the inflammatory response 110.
This finding of reducing protein C levels with increasing total WBC is in keeping with findings in T2DM patients.
CONCLUSIONS
The diabetics in the study population have a poor glycaemic control compared to the control group (8.22% v 5.66%, p <0.05).
The biochemical parameters studied did not show a risk for thrombosis. PT and INR of the subjects even though significantly shorter than that of the controls, were all within normal limits.
There were no statistical differences in the platelet counts, APTT and protein C antigen levels of the diabetics and the control group.
No correlations were found between biochemical parameters and glycaemic control of the diabetics studied.
The only factor associated with reduced protein C levels was an increase in total WBC.
RECOMMENDATIONS
Haemostatic screening in diabetics using PT / INR can be carried out.
The reason for having a poor glycaemic control in our diabetics should be investigated further.
REFERENCES
- Diagnosis and Classification of diabetes mellitus and its complications. World Health Organization Department of Non Communicable Disease Surveillance [Internet]. 1999; Available from: http://wholibdoc.who.int/hq/WHO_NDC_99.9.pdf
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- Sarah Wild, Gojka Roglic, Anders Green, Richard Sicree, H Global Prevalence of Diabetes.Estimates for the year 2000 and projections for 2030. Diabetes Care. 2004;27(5):1047–53.
- Yuankai Shi, Frank Hu The global implications of diabetes and cancer. The Lancet, June 7, 2014. vol 383, no 9933: 1947-1948
- Campbell DD, Parra MV, Duque C, Gallego N, Franco L, Tandon A, et Amerind ancestry, socioeconomic status and the genetics of type 2 diabetes in a Colombian population. PloS one [Internet]. 2012 Jan [cited 2012 Jul 24];7(4):e33570. Available from: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=3328483&to ol=pmcentrez&rendertype=abstract
