Peripheral Neuropathy and Associated Factors in Diabetics at the CNHU-HKM of Cotonou in 2021 ()
1. Introduction
Diabetes, according to the World Health Organisation (WHO), “is a chronic disease that occurs when the pancreas does not produce enough insulin or when the body is unable to use the insulin it produces effectively. The result is an increased concentration of glucose in the blood” [1]. Its prevalence varies between countries and ethnic groups. The condition is rapidly increasing in all countries of the world, particularly in developing countries. In Africa, 3.9% of adults aged 20 - 79 were living with diabetes in 2019. The largest increases will occur in developing countries [2] [3]. Between 2000 and 2016, according to WHO, premature mortality due to diabetes increased by 5% in these countries. Indeed, Benin is not spared from this epidemic trend. The prevalence of diabetes, which was 1.1% in 2001, doubled in 2008 (2.6%) according to the STEPS survey [4] and rose to 5.1% in 2016 [5]. The management of diabetes remains difficult in Africa, which exposes diabetics to multiple complications, particularly diabetic neuropathy, which has a high prevalence (8% to 60%) [6]. It is the most common complication, which can be responsible for trophic disorders in the foot leading to amputation, silent myocardial ischaemia (55% - 70% of deaths) [7], erectile dysfunction and other disorders causing discomfort in the daily life of patients. The present study was initiated to evaluate peripheral neuropathy and associated factors in diabetics at the Centre National Hospitalier Universitaire-Hubert Koutoukou MAGA (CNHU-HM) in Cotonou.
2. Study Methods
This was a cross-sectional and analytical study which took place during the period from 23 September to 23 December 2021 and involved diabetic patients followed up at the University Clinic of Endocrinology Metabolism Nutrition of the CNHU-HKM for the management of their diabetes. We did an exhaustive sampling. The study included diabetic patients who were seen in consultation or hospitalized at the University Clinic of Endocrinology Metabolism Nutrition of the CNHU-HKM during the study period; who gave their free and informed consent. Non-included patients were those with acute diabetic complications and those with other causes of neuropathy. The variables studied were age, sex, professional activity, education level. Hypertension, Diabetes duration, Diabetes control, Diabetes complications. We selected the DN4 screening questionnaire which is the most widely used. The collected data were exported from the KoboCollect® application into Excel version 2019 and analysed with the R software version 3.6.1. For comparisons, Pearson’s chi-2 test or Fisher’s exact test Student’s t-test was used. The threshold of statistical significance was 5%.
3. Results
At the end of our study, 155 patients were included.
Socio-demographic characteristics (Table 1).
The median age of the patients was 65 years with extremes ranging from 31 to 85 years and an interquartile range from 55 to 65 years. There were 88 (56.8%) female patients. The sex ratio (M/F) was 0.76. Retired patients were 37.4% and employed patients 42.3%. In addition, about 42.6% of the patients had secondary education and 39.4% had higher education. Fons and relatives represented 51.6% of our sample (Table 1).
Clinical features
Hypertension was present in 71% (110) of the patients, stroke in 5.2% and dyslipidaemia also in 55.5% (86 patients). The frequency of patients who drank alcoholic beverages at least once a month was 16.1% (25 patients) and those who occasionally smoked was 3.2% (Table 2).
Type of diabetes, treatment, length of time and control of diabetes
All patients had type 2 diabetes and 58.7% of these patients had suffered from diabetes for more than 5 years. The majority of patients (90.3%) were being treated with oral antidiabetic drugs. Diabetes imbalance was found in 54.8% of the patients (Table 3).
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Table 1. Socio-demographic characteristics of the patients surveyed. CNHU-HKM, Cotonou/Benin, 2021 (N = 155).
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Table 2. Distribution of patients according to history. CNHU-HKM, Cotonou/Benin, 2021 (N = 155).
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Table 3. Distribution of patients according to type of diabetes, treatment, length of time and diabetes control. CNHU-HKM, Cotonou/Benin, 2021 (N = 155).
ADO: Antidiabetic drugs: HbA1c: Glycated haemoglobin.
Anthropometric Measurements
Sixty-seven patients were overweight or 43.2% and 46 patients or 29.7% were obese. The average waist circumference of our patients was 93 cm. The majority of patients or 70.8% were abdominally obese.
Complications
All patients had a fundus examination. Of the patients, 20.6% had diabetic retinopathy. Erectile dysfunction was found in 7.1% of patients.
Prevalence of diabetic peripheral neuropathy (DPN)
Of the 155 patients surveyed, 54 had diabetic peripheral neuropathy, a prevalence of 34.8%. Factors associated with diabetic peripheral neuropathy.
Univariate analysis
Socio-demographic characteristics and diabetic peripheral neuropathy.
Clinical features and diabetic peripheral neuropathy.
➢ History and diabetic peripheral neuropathy
There was an association between high blood pressure (p = 0.001), dyslipidaemia (p = 0.006), smoking (p = 0.031) and the occurrence of diabetic peripheral neuropathy.
Obesity (p = 0.196), alcoholism (p = 0.647) and stroke (p = 0.714) were not associated with diabetic peripheral neuropathy (Table 4).
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Table 4. Association between hypertension, stroke, obesity, dyslipidaemia, alcoholism, smoking and diabetic peripheral neuropathy. CNHU-HKM, Cotonou/Benin, 2021 (N = 155).
➢ Type of treatment, length of time and imbalance of diabetes
Diabetes imbalance (p = 0.000) was associated with the occurrence of diabetic peripheral neuropathy.
Length of diabetes (p = 0.609) and type of treatment (p = 0.095) were not associated with diabetic peripheral neuropathy (Table 5).
➢ Complications
Erectile dysfunction (p = 0.0002) and diabetic retinopathy (p = 0.0003) were associated with diabetic peripheral neuropathy.
Multivariate analysis
Factors associated with DPN on multivariate analysis were gender (Table 6).
(p = 0.022), hypertension (p = 0.017), dyslipidaemia (p = 0.015), diabetic imbalance (p < 0.001), diabetic retinopathy (p = 0.020) and erectile dysfunction (p < 0.001).
Diabete imbalance, erectile dysfunction and diabetic retinopathy were associated with DPN on multivariate analysis were (Table 7).
4. Discussion
The prevalence of diabetic peripheral neuropathy among diabetics in our study was 34.84%. Several authors have reached a similar result. Fendi et al. 33.3% in Tunisia in 2011 [8], Aynaou et al. 43% in Morocco in 2019 [9], Doukpo et al. 47.6% in Benin in 2015 [10], Djibril et al. 43.2% in Mali in 2013 [11]. However, Boufaida et al. in Morocco (2016) [12] and Mizouri et al. in Tunisia (2018) [13], reported lower prevalences of 17.5% and 8.6% respectively. This difference could be explained by the disparity of the criteria used.
Factors associated with diabetic peripheral neuropathy.
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Table 5. Association between the type of treatment, the length of time and the imbalance of diabetes and diabetic peripheral neuropathy. CNHU-HKM, Cotonou/Benin, 2021.
ADO: Oral antidiabetics, HbA1c.
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Table 6. Study of factors associated with diabetic peripheral neuropathy in multivariate analysis. CNHU-HKM, Cotonou/Benin, 2021.
Gender was a factor statistically associated with diabetic peripheral neuropathy. Moreover, DPN was more frequent in women (p = 0.022). Aouiche et al. in Algeria (2014) [14], Fendi et al. in Tunisia (2011) [8] found the same association. On the other hand, in the study by Doukpo et al. in Benin (2015) [10] and that of Aynaou et al. in Morocco (2019) [9], a correlation between sex and diabetic peripheral neuropathy was not reported.
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Table 7. Study of factors associated with diabetic peripheral neuropathy in multivariate analysis. CNHU-HKM, Cotonou/Benin, 2021.
Age was not a factor associated with DPN in our study. Boufaida et al. [12] made the same finding in 2016 in Morocco. On the other hand, AOUICHE et al. [14], and AYNAOU et al. [9] reported an association respectively in Algeria (2014) and Morocco (2019). This difference could be explained by the different sample size.
There was an overall association between occupation and the occurrence of diabetic peripheral neuropathy. The prevalence of diabetic peripheral neuropathy was lower among civil servants compared to craftsmen/workers and housewives. This finding could be explained by the fact that civil servants are generally well off and some of them have health insurance that allows them to better manage their diabetes than others.
Educational level was significantly related to diabetic peripheral neuropathy. The prevalence of DPN was higher in less educated patients (illiterate or primary). This could be explained by the fact that less educated patients are not always well informed about diabetes and are therefore more exposed to chronic complications including diabetic peripheral neuropathy.
This association between occupation and DPN, education level and DPN was also reported by the study of Doukpo et al. in Benin (2015) [10].
DPN is significantly associated with hypertension in some studies such as those of Boufaida et al., Aouiche et al. and Tesfaye et al. conducted respectively in Morocco (2016), Algeria (2014) and sixteen (16) European countries (1995) [12] [14] [15], including ours where 42.73% of patients with diabetic peripheral neuropathy also had hypertension (p = 0.001).
An association between smoking and DPN was also found in our study. This result is similar to that of Tesfaye et al. in 1995 [15] and AL Mahroos et al. in Bahrain (2003) [16] who found an association.
We did not find an association between alcohol consumption and the occurrence of diabetic peripheral neuropathy. This may be explained by the sample size.
Overweight (obesity) was not associated with diabetic peripheral neuropathy. Djibril et al. in 2013 in Mali [11] made the same observation. On the other hand, AL Mahroos et al. [16] found an association between excess weight and the occurrence of diabetic peripheral neuropathy in Bahrain in 2006. This difference can be explained by the small size of our sample.
Dyslipidemia is involved in the mechanism of nerve destruction that leads to diabetic peripheral neuropathy. Boufaida et al. 2016 (Morocco) [12] and Lahmar et al. in 2017 (Morocco) [17] noted in their studies conducted in Morocco a significant relationship between dyslipidemia and the prevalence of diabetic peripheral neuropathy. Dyslipidemia (p = 0.015) is also associated with diabetic peripheral neuropathy in our study.
Diabetic imbalance was associated with diabetic peripheral neuropathy. This result is consistent with the literature. Indeed, in case of poor diabetic control, there is an increased production of AGEs which are involved in the occurrence of diabetic peripheral neuropathy. This result is similar to that reported by Aouiche et al. in Algeria, Al Mahroos et al. in Bahrain (2006), Boru et al. in Turkey (2007), Ugoya et al. Nigeria (2008) and Bouya et al. in Iran (2005) [14] [16] [18] [19] [20], where diabetic imbalance is associated with diabetic peripheral neuropathy. On the other hand, Doukpo et al. in 2015 in Benin [10] and Mahamane et al. in 2014 in Niger [21] had not reported an association. It has not been established that the risk of diabetic peripheral neuropathy increases with the age of diabetes. Similarly, Oueslati et al. [22] reached the same conclusion in 2018 in Tunisia. On the other hand, Al Mahroos et al. [16], Ugoya et al. [19], concluded that chronic complications of diabetes appear with the duration of diabetes respectively in Bahrain (2006) and Nigeria (2008).
Erectile dysfunction was associated with diabetic peripheral neuropathy (p = 0.001) and this result is similar to that reported by Mahamane et al. in 2014 in Niger [21].
Diabetic retinopathy was significantly related to diabetic peripheral neuropathy. Similarly Boufaida et al., Aynaou et al., Ugoya et al., and Mahamane et al. [9] [12] [19] [21] also made the same finding respectively in Morocco (2016), Morocco (2019), Nigeria (2008) and Niger (2014). This result is not surprising because diabetic retinopathy shares the same pathophysiological mechanism with diabetic peripheral neuropathy which is the increase of AGEs promoted by chronic hyperglycaemia.
5. Conclusion
At the end of this study which focused on diabetic peripheral neuropathy and associated factors in diabetics followed at the University Clinic of Endocrinology Metabolism Nutrition of the CNHU-HKM of Cotonou, Benin in 2021, it appears that the prevalence of diabetic peripheral neuropathy is high 34.84% in the diabetics included in the study. The factors associated with diabetic peripheral neuropathy are: gender, occupation, level of education, arterial hypertension, dyslipidaemia, smoking, diabetic imbalance, erectile dysfunction, diabetic retinopathy. The determination of these risk factors is essential for the identification of patients at risk and better management.