The SA Journal Diabetes & Vascular Disease Vol 15 No 1 (July 2018)

SA JOURNAL OF DIABETES & VASCULAR DISEASE

RESEARCH ARTICLE

VOLUME 15 NUMBER 1 • JULY 2018

Discussion

This study showed that a statistically significant proportion of the

diabetic group belonged to the high cardiovascular risk category,

compared to the groupwith themetabolic syndrome and the healthy

control group, despite being on treatment. Diabetes is a major risk

factor for CVD,

4,5

and findings by Haffner

et al

suggested that

patients with type 2 diabetes without previous myocardial infarction

have as high a risk of myocardial infarction as non-diabetic patients

with previous myocardial infarction, indicating that type 2 diabetes

is a coronary heart disease equivalent.

23,24

A recent meta-analysis by Bulugahapitiya and colleagues,

however, did not support this hypothesis, asserting that it was not

the diabetic status

per se

but the additional coronary artery disease

risk factors that confer the coronary artery disease equivalent state

in diabetic subjects. However, more than 70% of patients with type

2 diabetes die of cardiovascular causes.

Chronic hyperglycaemia has been implicated in the microvascular

complications of diabetes, and more recently it has also been

associated with the macrovascular complications of CVD, including

coronary heart disease, stroke and peripheral vascular disease.

A higher proportion of subjects with the metabolic syndrome

in our study were in the medium CVD risk category. The metabolic

syndrome is an insulin-resistant state and several studies have

shown that insulin resistance, characterised by impaired glucose

tolerance (two-hour plasma glucose levels between 7.8 and 11.0

mmol/l) or impaired fasting glucose (plasma glucose between 5.6

and 6.9 mmol/l) have about a two-fold higher risk for CVD events

than normoglycaemic subjects.

Glycated haemoglobin level, a surrogate marker of chronic

hyperglycaemia, has correlated strongly with the micro- and

macrovascular complications of diabetes.

A glycated haemoglobin

level less than 6% was the target of the intensive-treatment arm

of the Diabetes Control and Complications Trial (DCCT) and the

Epidemiology of Diabetes Interventions and Complications (EDIC)

studies, which recorded a significant 42% reduction in CVD

outcomes and a significant 57% reduction in the risk of non-

fatal myocardial infarction, stroke or CVD death, compared with

those previously in the standard-treatment arm with a glycated

haemoglobin target of 7–8%.

From our study, only about 50% of the diabetics achieved an

HbA

target of < 7%

and this may explain the high proportion

of diabetes patients in the high CVD risk category.

Chronic hyperglycaemia alone cannot explain the relationship

between diabetes and CVD.

Findings from the United Kingdom

Prospective Diabetes Study (UKPDS) group

showed that the most

important risk factors for coronary heart disease were classic risk

factors, particularly dyslipidaemia. In this study, the diabetic group

also had higher glycated haemoglobin values and lower HDL-C

values than the non-diabetic groups with and without the metabolic

syndrome, which further explains their increased CVD risk.

This study showed that the diabetics on treatment had

comparable TC, LDL-C and TG values with the healthy controls,

although only 40% of the diabetics met the LDL-C treatment

target of < 2.6 mmol/l.

The group with the metabolic syndrome

had significantly higher levels of TC, LDL-C and TG. Lifestyle

modification rather than drug therapy has been the management

option for CVD risk factor levels above the cut-off point for the

metabolic syndrome.

This study shows that a very low percentage

of the study population participated in physical exercises, side-

lining one of the avenues to target weight loss, reduce insulin

resistance and effectively control the metabolic syndrome and its

components.

Correlationanalysisinthisstudyidentifiedchronichyperglycaemia,

obesity and level of education as factors associated with CVD risk

in this population. Alcohol consumption and smoking were not

associated with CVD risk in this population, compared to other

climes,

probably because a very low percentage of the study

population smoked or used alcohol.

A study by Khaw

et al

reported that increasing values of

glycated haemoglobin > 5% was associated with cardiovascular

mortality and all-cause mortality in diabetic men, and glycated

haemoglobin also appeared to be a continuous risk factor for

cardiovascular mortality in the non-diabetic population. Strategies

to reduce glycaemia in both diabetic and non-diabetic populations,

including creating awareness of the effectiveness of increased

physical activity and weight reduction in reducing insulin resistance,

and increasing literacy levels would help reduce CVD risk scores in

adult Nigerians.

Conclusion

Cardiovascular risk factors were high in these adult Nigerians with

type 2 diabetes. Strategies to control the cardiovascular risk factors

of the metabolic syndrome, achieve better glycaemic control and

increase literacy levels would help to achieve cardiovascular risk

reduction in adult Nigerians.

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