CARDIOVASCULAR JOURNAL OF AFRICA • Volume 34, No 4, September/October 2023 240 AFRICA patients with DM (p = 0.039). However, that can be explained by the fact that our study pool consisted of a group of diabetics whose pre-operative cardiological complications were generally more prevalent. Altinbas and co-workers suggest no significant difference in post-operative cardiac events, and noted that after CEA a consequent coronary insufficiency occurred in 2.3% of cases, with no difference observed between the groups concerned.19 Ombrellaro et al. recently observed in post-CEA patients undesirable cardiac events such as MI and CHF in 14.3% of patients with diabetes and in 16% of the non-diabetic group. The difference was not statistically significant.20 The frequency of haematoma of the operated wound occurred in 2.4% of non-DM patients and in 3.6% of DM patients, while wound infection was present in only patients with DM (1.8%). Zhao et al. stated that the incidence of haematoma was relatively high in diabetics, the cause being pre-operative high doses of heparin (1 mg/kg), as well as double antiaggregation therapy.17 The same authors specify that diabetes may increase the possibility of wound and systemic infection, and that pre-operative HbA1c levels should be about 7% to reduce possible infections.17 Post-operatively, 50% carotid restenosis in the course of one year was not significant; it occurred in 2.2% of non-DM patients and in 1.8% of DM patients (χ2 = 0.124; p = 0.724). Other investigations produced similar results.19 Total post-operative mortality (neurological and cardiological) was present in 0.9% of non-diabetics and in 2.5% of diabetics (p = 0.113). Ahari et al. report in their study that diabetics had higher 30-day mortality rates (3.2 vs 1.4%; p = 0.02).5 Total post-operative complications were observed in 8.5% of non-diabetics and in 18.3% of DM patients (p < 0.001). DM patients were at more than two times greater risk of suffering from post-operative complications. Dorigo et al. found that the risk of post-operative complications was twice as high in patients suffering from DM.6 The study by Jeong et al. concluded that DM patients were not at a greater risk of 30-day morbidity and mortality after CEA than those without DM.16 Our patients on oral antidiabetics suffered considerably more often from post-operative complications than those on insulin (25.4 vs 8.2%; p < 0.001). In the study by Axelrod et al. there was a somewhat higher percentage of post-operative complications in the diabetics, although without a significant difference between the patients on insulin and those on oral antidiabetics.21 Dimić et al. have shown the cumulative rate of TIA/cerebrovascular infarction (p = 0.02) to be greater in insulin-dependent diabetics (IDDM) than in those who are insulin independent (IIDM).22 Similarly, Bennett et al. stated that insulin-necessitated DM is one of the independent predictors of high morbidity and mortality rates among the patients who have undergone CEA.23 However, Dorigo and co-workers discovered that patients with diabetes were at greater risk of death, but with no difference between the patients with insulin-controlled diabetes and those on oral medication.6 Parlani and colleagues reported that patients with IDDM had higher rates of cerebrovascular infarction and death (6.5 vs 1.7%; p = 0.02) than non-diabetics.7 Comparably, Pothof et al. stated that patients with IDDM had higher rates of 30-day cerebrovascular infarction and death than those without diabetes (3.4 vs 1.5%; p < 0.001).24 In our series, a more significant rate of mortality and postoperative complications occurred in diabetics being treated with oral antidiabetics, compared to those being treated with insulin, which conflicts with other studies that reported a higher frequency of complications in groups on insulin therapy. To some extent, this can be explained by extremely lengthy and irregular therapy of patients on oral antidiabetic agents, which leads to chronic, atherosclerotic changes in the blood vessels. Patients on insulin may be more diligent in their therapy. With regard to long-term regulation of glycaemia, our patients with post-operative complications had significantly higher values of HbA1c (t = 5.010; p < 0.001). Tanashian et al. reported that the presence of DM was associated with an increased risk of ischaemic lesions in the brain and a higher percentage of post-operative complications, associated with increased values of glycaemia (8.0 mmol/l) and HbA1c (7.8–8%) in the pre-operative phase.25 Dimić et al. stated that the group of diabetics with HbA1c > 7% had a greater cumulative rate of TIA/ cerebrovascular infarctions (p = 0.03).22 Parr et al. reported that patients with IDDM, when compared to those with IIDM, had higher rates of cerebrovascular infarction (3.27, 0.93 and 0.94%; p < 0.0001), MI (3.35, 1.10 and 0.87%, p < 0.0001) and hospital mortality (p < 0.0001).26 Jeong et al. have shown that insulin use was associated with a higher rate of mortality and morbidity. The absence of data on serial measurements of HbA1c levels in their analysis was the reason they could not explain differences in glycaemic control.16 It is certain that high concentrations of low-density lipoprotein and chronic hyperglycaemia, indicated by high HbA1c levels, increases the development of atherosclerosis, which sets in earlier and is more pervasive in diabetics. On the basis of the results of our investigation, it is believed that the percentage of post-operative complications may be reduced by means of a better regulation of glycaemia, lower values of HbA1c, prompt diagnosis of glucose intolerance and regular and adequate antidiabetic therapy. Considering the small number of studies that have dealt with this kind of investigation of complications related to diabetes therapy, the hypothesis remains to be proven in similar future randomised studies. Conclusions In comparison to other studies, this research, possibly for the first time, included a large number of patients for a short time period, a high percentage of diabetics were included, the investigation was conducted in diabetics on different types of antidiabetic therapy, and the occurrence of complications was determined according to values of glycosylated haemoglobin. The results of this study indicate that diabetes was an independent risk factor for fatal and non-fatal cardiac or neurological events after CEA since it caused 2.5 times more post-operative complications in the group of diabetic patients. Our study also recorded a higher rate of mortality and post-operative complications, as well as higher HbA1c values in the diabetics on oral antidiabetics than in those on insulin therapy. This was in conflict with similar studies. Ultimately, these results show that CEA was a reliable and efficient method of surgical treatment of the patients with significant carotid stenosis and concomitant diabetes mellitus, regardless of the type of antidiabetic therapy.
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