Diabetes is a major public health problem, increasingly affecting millions of people across the globe [
The pathophysiology of ED in DM is related to multiple mechanisms, including endothelial dysfunction, the accumulation of advanced glycation end products, oxidative stress, and autonomic neuropathy [
Large differences have been reported on the prevalence of ED in patients with DM in different studies. For instance, ED has been reported in 49% of the male population in England [
Patients with ED often suffer from poor quality of life [
Electronic databases, such as PubMed, Google Scholar, African Journals Online, Scopus, Web of Science, PsycINFO, and the Cochrane library, were independently and systematically searched by the authors. In addition, a manual search of gray literature and other related articles were deployed to identify additional relevant research. Data from the International Diabetic Federation (IDF) were also searched and used. This search involved articles published from January 1, 1990, to September 4, 2019. The searches were restricted to full texts, free articles, human studies, and English-language publications. Authors were contacted for full texts of their articles through e-mail, if necessary. The search was conducted using the following terms and phrases: “erectile dysfunction,” “sexual dysfunction,” “impotence,” “diabetes mellitus,” and “Africa.” Boolean operators like “AND” and “OR” were used to combine search terms. Particularly, to fit the advanced PubMed database, the following search strategy was used (“erectile dysfunction” OR “impotence” OR “sexual dysfunction”) AND (“diabetes mellitus”) AND (“Africa”).
This review considered studies that included adult male patients aged 18 years or older who had been diagnosed with DM.
In this meta-analysis, patients with DM whose BMI was ≥30 kg/m2 and glycated hemoglobin was >7% were considered as exposed variable to estimate its effect on ED.
In this meta-analysis, patients with DM whose BMI was 18.5–24.9 kg/m2 and glycated hemoglobin was <7% were considered as control variable for ED.
The outcome of this study was the prevalence of ED among men with DM.
This systematic review included observational studies such as retrospective or prospective cohort studies, and cross-sectional and case-control studies, where ED among DM patients has been reported.
Studies were included in the meta-analysis if they adhered to the following guidelines: (1) all observational studies needed to report the prevalence of ED; (2) articles must be published in peer-reviewed journals or gray literature; (3) articles must be published in English between 1990 and 2019; and (4) studies must examine an African population and include male participants. Studies were excluded if (1) they were not fully accessible; (2) studies with duplicated citation; (3) they possessed a poor quality score as per the stated criteria; (4) they failed to determine the desired outcome (i.e., ED); or (5) they included only females.
Two independent investigators screened the title and abstract of all of the potential studies to be included in our analysis. Data were extracted from each of these studies using the standardized data extraction format prepared in a Microsoft Excel worksheet by the three authors independently. For each article, we extracted data regarding the names of the authors, year of publication, study area, study design, sample size, data collection year, sampling technique, diagnostic criteria used for ED, reported prevalence with its 95% confidence interval (CI), and information regarding the associated factors. When some information was missing, first or corresponding authors of the article were contacted at least twice in a month to obtain the variables of interest. The quality of each included study was assessed using the Newcastle–Ottawa scale (NOS) [
To obtain the pooled effect size, a meta-analysis using the random-effects DerSimonian and Laird model was performed [
To estimate the overall prevalence of ED in patients with DM, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was used [
In the first step of our search, 1,622 studies were retrieved. About 1,617 studies were found from seven international databases, and the remaining 5 were through a manual search. The databases included PubMed (43), Scopus (28), Google Scholar (800), Web of Science (317), Cochrane Library (3), PsycINFO (19), and African Journals Online (407). Of these, 879 duplicate records were identified and removed. From the remaining 743 articles, 677 articles were excluded after reading the titles and abstracts based on the predefined eligibility criteria. Finally, 66 full-text articles were assessed for their eligibility. Based on the predefined criteria and quality assessment, only 13 articles were included for the final analysis (Figure
PRISMA flow chart for study selection.
In the current meta-analysis, a total of 13 studies with 3,501 study participants were included to estimate the pooled prevalence of ED among DM patients. With respect to study design, the majority (95%) of the studies included were cross sectional. The studies varied substantially in sample size, ranging from 70 to 599. The highest prevalence (95%) of ED was reported in a study conducted in South Africa [
Regarding the sampling technique employed, 7 of the studies [
Baseline characteristics of the included studies.
First author | Publication year | Country | Study design | Sample size | Prevalence of ED (95% CI) | Data collection year | Data collection tool | Sampling technique | Quality score (10) |
---|---|---|---|---|---|---|---|---|---|
Baldé et al. [ |
2006 | Guinea | Cross-sectional | 187 | 48 (40.8, 55.2) | NR | International Index of Erectile Function | NR | 7 |
El Saghier et al. [ |
2015 | Egypt | Cross-sectional | 70 | 85.7 (77.5, 93.9) | March 2014 to January 2015 | International Index of Erectile Function-5 | Consecutive | 7 |
Kemp and Rheeder [ |
2015 | South Africa | Cross-sectional | 150 | 95 (91.5, 98.5) | NR | The Sexual Health Inventory for Men | Simple random | 7 |
Likata et al. [ |
2012 | Kenya | Cross-sectional | 350 | 68.8 (63.9, 73.6) | NR | International Index of Erectile Function | Consecutive | 7 |
Lokrou and Soumahoro [ |
2011 | Ivory coast | Cross-sectional | 112 | 74.1 (65.9, 82.2) | NR | International Index of Erectile Function | Consecutive | 7 |
Mutagaywa et al. [ |
2014 | Tanzania | Cross-sectional | 312 | 55.1 (49.5, 60.6) | May to December 2011 | International Index of Erectile Function | NR | 7 |
Olarinoye et al. [ |
2006 | Nigeria | Cross-sectional | 77 | 74 (64.2, 83.8) | NR | International Index of Erectile Function | Consecutive | 7 |
Owiredu et al. [ |
2011 | Ghana | Cross-sectional | 300 | 67.9 (62.4, 73.3) | November 2010 to March 2011 | Golombok Rust Inventory of Sexual SATISFACTION | Consecutive | 7 |
Pasipanodya Ian Machingura [ |
2018 | Zimbabwe | Cross-sectional | 348 | 73.9 (69.3, 78.5) | October 23, 2013 to July 9, 2014 | International Index of Erectile Function | Consecutive | 6 |
Seid et al. [ |
2017 | Ethiopia | Cross-sectional | 249 | 69.9 (64.2, 75.6) | January 1–February 30, 2016 | International Index of Erectile Function | Systematic random | 8 |
Ugwumba et al. [ |
2018 | Nigeria | Cross-sectional | 325 | 94.7 (92.2, 97.1) | September 2016 to December 2017 | International Index of Erectile Function | Consecutive | 7 |
Walle et al. [ |
2018 | Ethiopia | Cross-sectional | 422 | 85.5 (82.1, 88.8) | January to March 2016 | International Index of Erectile Function | Systematic | 6 |
Webb et al. [ |
2014 | South Africa | Cluster randomized control trial | 599 | 36 (32.1, 39.8) | NR | Sexual Health Inventory For Men | Systematic | 8 |
NR; not reported.
Our meta-analysis using the random-effects model showed that the estimated overall prevalence of ED in patients with DM was 71.45% (95% CI: 60.22–82.69) with a significant level of heterogeneity (
Forest plot of the prevalence of erectile dysfunction in patients with diabetes mellitus.
To overcome the presence of heterogeneity, subgroup analysis using country, publication year, sample size, and sampling technique was done. Based on this, the prevalence of ED was found to be 84.92% in Nigeria, 73.33% in studies published since 2010, and 74.51% in studies with a sample size less than 300 (Table
The prevalence of erectile dysfunction and estimates of heterogeneity when publications are divided into different subgroups.
Sub-group | Category | No. of studies included | Sample size | Prevalence (95% CI) |
|
|
---|---|---|---|---|---|---|
By year of publication | Before 2010 | 2 | 264 | 60.78 (35.3, 86.25) | <0.001 | 94.3 |
2010 and above | 11 | 3,237 | 73.33 (61.23, 85.44) | <0.001 | 98.8 | |
|
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Sample size | <300 | 6 | 845 | 74.51 (59.54, 89.5) | <0.001 | 97 |
≥300 | 7 | 2,656 | 68.88 (52.17, 85.58) | <0.001 | 99.2 | |
|
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Country | Nigeria | 2 | 402 | 84.92 (64.66, 105.17) | <0.001 | 93.8 |
South Africa | 2 | 749 | 65.51 (7.9, 123.32) | <0.001 | 99.8 | |
Ethiopia | 2 | 671 | 77.88 (62.59, 93.16) | <0.001 | 95.3 | |
Others | 7 | 1,679 | 67.52 (59.45, 75.59) | <0.001 | 92.2 | |
|
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Sampling technique | Systematic | 3 | 996 | 83.63 (71.6, 95.66) | <0.001 | 97.1 |
Simple random | 1 | 70 | 85.7 (77.5, 93.9) | 0.1 | 0.1 | |
Consecutive | 7 | 2,136 | 67.22 (50.2, 84.24) | <0.001 | 98.5 | |
Not specified | 2 | 299 | 60.98 (35.40, 86.55) | <0.001 | 95.5 |
To identify the sources of heterogeneity, meta-regression analysis was undertaken by considering year of publication, sample size, and sampling technique. However, our results showed that the covariates were not significantly associated with the presence of heterogeneity (Table
Meta-regression analysis for the included studies to identify the sources of heterogeneity.
Variables | Category | Coef. | Std. err. |
|
|
(95% conf. interval) |
---|---|---|---|---|---|---|
By year of publication | Before 2010(reference) | 0.421 | 1.106 | 0.38 | 0.771 | (−2.043 to 2.88) |
2010 and above | ||||||
|
||||||
Sample size | <300 (reference) | −0.041 | 0.487 | −0.08 | 0.934 | (−1.126 to 1.044) |
≥300 | ||||||
|
||||||
Sampling technique | Systematic | 0.614 | 1.267 | 0.51 | 0.628 | (−2.35 to 3.63) |
Simple random | 0.254 | 1.85 | 0.14 | 0.895 | (−4.13 to 4.64) | |
Consecutive | 0.202 | 1.219 | 0.17 | 0.873 | (−2.68 to 3.08) | |
Not specified (reference) |
To evaluate the effect of an individual study on the pooled effect size, sensitivity analysis was conducted. Sensitivity analyses using the random-effects model revealed that no single study influenced the overall prevalence of ED in DM patients (Figure
Sensitivity analysis of the 13 studies.
We found that there was no publication bias among the included studies, as depicted by the symmetrical distribution of our funnel plot (Figure
Funnel plot for the presence of publication bias among the 13 included studies.
The pooled effects of five studies showed that BMI of ≥30 kg/m2 was not statistically associated with ED in patients with DM (Figure
The pooled effects of body mass index on erectile dysfunction.
According to our current meta-analysis, those who had normal glycated hemoglobin were 7% less likely to develop ED compared with those who had a glycated hemoglobin value ≥7%, although this association was not statistically significant (OR: 0.93; 95% CI: 0.15–5.91) (Figure
The pooled effects of glycated hemoglobin ≥7% on erectile dysfunction.
The prevalence of ED in this meta-analysis was estimated to be 71.45% in patients with DM. This indicates that ED is highly prevalent in diabetic patients and is an inadequately controlled complication of DM in African populations. Hence, a serious and multifactorial approach is required to manage diabetes-related ED, with emphasis being placed on treatment adherence, self-care, and health information dissemination.
Our estimated prevalence of ED in DM patients in Africa is substantially higher than that reported in a systematic review and meta-analysis conducted at the global level, which sets the prevalence at 52.5% [
The subgroup analysis in this study showed that the pooled prevalence of ED among diabetic patients in Nigeria was 84.92% (95% CI: 64.66–105.17), which was the highest among the African nations examined, including the prevalence in Ethiopia (77.88%; 95% CI: 62.59–93.16) and South Africa (65.5%; 95% CI: 7.9–123.3). This variation might be due to differences in health-seeking behavior between the populations, differences in the diagnostic methods, and sociodemographic characteristics.
Though we identified two factors (BMI and glycated hemoglobin) that may be related to ED in DM patients, a BMI of ≥30 kg/m2 and glycated hemoglobin of ≥7% were not significantly associated with ED among diabetic patients. Specifically, we found that those who had BMI of ≥30 kg/m2 were 26% more likely to develop ED, although the increase was not statistically significant. This is supported by studies conducted on populations in Vietnam [
This study has clinical implications in that the high prevalence of ED in DM patients should guide health care professionals to increase patient awareness of DM complications and design preventive measures and treatments to improve patient quality of life. In addition, identifying associated factors may help health care professionals treat DM patients with ED during their clinical care.
The meta-analysis conducted in this study has several limitations that should be considered in future research. First, it is difficult to determine if the results from various countries is representative of the entire content because no data were found for all of Africa. Second, only English articles were considered, and thus, we could be missing important data published in other languages. Moreover, as mentioned previously, we did not identify all of the potential predictors of ED among patients with DM. Therefore, further study is needed to identify associated factors for the development of ED among patients with DM may be necessary, such as age, duration of diabetes, preexisting illness, sedentary lifestyle, and smoking.
This study revealed that the prevalence of ED remains high in DM patients in Africa. That said, the prevalence of ED differed by country. Therefore, situation-based interventions and country context-specific preventive strategies should be developed to reduce the prevalence of ED among patients with DM.
Adjusted odds ratio
Confidence interval
Diabetes mellitus
Erectile dysfunction
International Diabetic Federation
Preferred Reporting Items for Systematic Reviews and Meta-Analyses.
The authors declare that they have no competing interests.
WSS and TYA developed the protocol and were involved in the design, the selection of the studies, data extraction, statistical analysis, and the development of the initial drafts of the manuscript. YAA and TYA were involved in data extraction, quality assessment, statistical analysis, and revising the manuscript. WSS and YAA prepared the final draft of the manuscript. All authors read and approved the final draft of the manuscript.
Supplementary file 1: methodological quality assessment of cross-sectional studies using modified Newcastle–Ottawa Scale (NOS).