Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates constitute the members of the Gulf Cooperation Council (GCC) and have high prevalence rates of type 2 diabetes [
Elsewhere in the Middle East, diabetes is also prevalent, mirroring the current global epidemic of diabetes [
Complications of diabetes contribute greatly to the increased mortality and morbidity associated with this disease. Diabetic complications are customarily divided into two main categories: macrovascular complications, including heart disease and stroke, and microvascular complications, which include retinopathy, nephropathy, and neuropathy. In the multinational A1chieve study, a large global study, based on nearly 68,000 type 2 diabetics, microvascular complications accounted for about half the total number of complications [
Microvascular complications, the focus of this report, are a leading cause of blindness, kidney failure, and lower limb amputation. It is unclear why some diabetic patients develop microvascular complications and other patients do not. Previous investigators have pointed out that the links between the various microvascular complications need further exploration [
The aims of this study performed in the type 2 diabetic adult population of Qatar were to (1) examine the frequency and overlap of microvascular complications, (2) determine risk factors for individual diabetic complications, and (3) determine if smoking, a risk factor for diabetes, was also associated with microvascular complications.
The information in this report came from a cross-sectional survey conducted among patients attending the outpatient clinics of Hamad General Hospital, the largest tertiary care hospital in Doha, the capital of Qatar. Data were collected from June 2013 to January 2015 using a detailed questionnaire (supplementary file available on request) covering patient background information, health status, tobacco use, chronic disease history, and family history. Trained personnel from the Division of Global and Public Health (now Institute for Population Health), Weill Cornell Medicine-Qatar, completed the questionnaire while interviewing patients at the time of their clinic visit. The patients were recruited from the diabetic, endocrine, gastroenterology, ophthalmology, nephrology, dietetic, podiatry, and smoking cessation clinics. The inclusion criteria for recruitment were age ≥ 18 and previous diagnosis of diabetes. Exclusion criteria included subjects less than 18 years of age, subjects diagnosed with type I diabetes, and those with gestational diabetes. In addition to information obtained directly from patients, the interviewer also collected information from the patient’s chart relating to current findings on physical examination, medication use, and laboratory data. Detailed smoking questions were included in the questionnaire because smoking is a known risk factor for diabetes, but its relationship to various complications has not been well documented. Because of the low prevalence of smoking in the female population of this region (less than one percent of Qatari women smoke, and the prevalence of smoking in non-Qatari women is only about 3%) [
The study was reviewed and approved by the Research Office at Weill Cornell Medicine-Qatar and the Research Committee at Hamad Medical Corporation. Patient participation in the study was entirely voluntary, and less than 2% of patients who were approached opted out of the study. Prior to the interview, a statement regarding the study embodying the elements of consent was read out to the subjects and verbal consent was obtained from each recruited subject.
The study sample size (800 men) was calculated to detect a 10% difference in the prevalence of complications among male diabetic smokers, corresponding to an odds ratio = 1.5, assuming that 45% of men ever smoked and that the prevalence of complications is 50% in nonsmokers, using a two-sided
Table
Participant characteristics.
All | Number of complications | ||||
---|---|---|---|---|---|
Patients | None | 1 | ≥2 | ||
All | 1034 (100) | 534 (100) | 318 (100) | 182 (100) | |
Age (mean, SD), years | 55 ± 10 | 53 ± 11 | 57 ± 10 | 59 ± 9 | <0.0001 |
Sex | |||||
Males | 798 (77.2) | 442 (82.8) | 228 (71.7) | 128 (70.3) | |
Females | 236 (22.8) | 92 (17.2) | 90 (28.3) | 54 (29.7) | <0.0001 |
Nationality | |||||
Qatari | 419 (40.5) | 202 (37.8) | 127 (39.9) | 90 (49.5) | |
Non-Qatari | 615 (59.5) | 332 (62.2) | 191 (60.1) | 92 (50.5) | 0.01 |
Education | |||||
≤High school | 538 (52.0) | 250 (46.8) | 170 (53.5) | 118 (64.8) | |
>High school | 496 (48.0) | 284 (53.2) | 148 (46.5) | 64 (35.2) | <0.0001 |
Household monthly income | |||||
<$2750 | 257 (33.3) | 140 (32.7) | 74 (32.3) | 43 (37.1) | |
$2750–5500 | 235 (30.4) | 126 (29.4) | 72 (31.4) | 37 (31.9) | |
≥$5500 | 281 (36.3) | 162 (37.9) | 83 (36.2) | 36 (31.0) | 0.26 |
Family history of diabetes | |||||
No | 348 (35.1) | 211 (40.5) | 100 (33.8) | 37 (21.3) | |
Yes | 643 (64.9) | 310 (59.5) | 196 (66.2) | 137 (78.7) | <0.0001 |
Duration of diabetes | |||||
Less than 10 years | 453 (43.8) | 330 (61.8) | 102 (32.1) | 21 (11.5) | |
10 or more years | 581 (56.2) | 204 (38.2) | 216 (67.9) | 161 (88.5) | <0.0001 |
Age at onset of diabetes, years | 43 ± 11 | 44 ± 10 | 43 ± 11 | 39 ± 11 | <0.0001 |
HbA1c, percent | 8.3 ± 1.8 | 8.0 ± 1.8 | 8.4 ± 1.7 | 9.0 ± 1.9 | <0.0001 |
Treatment for diabetes | |||||
Drug | 549 (53.6) | 338 (64.1) | 162 (51.3) | 49 (26.9) | |
Insulin | 436 (42.5) | 161 (30.6) | 145 (45.9) | 130 (71.4) | |
Other | 40 (3.9) | 28 (5.3) | 9 (2.9) | 3 (1.7) | <0.0001 |
BMI, kg/m2 | 30.8 ± 6.5 | 30.1 ± 6.4 | 31.1 ± 6.4 | 32.1 ± 6.9 | 0.001 |
Normal weight | 163 (17.5) | 94 (19.8) | 45 (15.6) | 24 (14.5) | |
Overweight | 320 (34.5) | 177 (37.3) | 92 (31.9) | 51 (30.7) | |
Obese | 446 (48.0) | 204 (42.9) | 151 (52.4) | 91 (54.8) | 0.005 |
Smoking status | |||||
Never smoked regularly | 665 (64.3) | 335 (62.7) | 202 (63.5) | 128 (70.3) | |
Ever smoke regularly | 369 (35.7) | 199 (37.3) | 116 (36.5) | 54 (29.7) | 0.10 |
LDL, mmol/L | 2.5 ± 0.9 | 2.6 ± 0.9 | 2.4 ± 0.9 | 2.4 ± 1.0 | 0.02 |
Cholesterol, mmol/L | 4.4 ± 1.1 | 4.5 ± 1.1 | 4.3 ± 1.1 | 4.2 ± 1.3 | 0.05 |
Creatinine, |
93 ± 52 | 83 ± 34 | 94 ± 49 | 120 ± 80 | <0.0001 |
≤106 |
819 (80.5) | 475 (91.4) | 241 (76.5) | 103 (56.6) | |
>106 |
198 (19.5) | 45 (8.6) | 74 (23.5) | 79 (43.4) | <0.0001 |
History of hypertension | |||||
No | 361 (34.9) | 236 (44.2) | 89 (28.0) | 36 (19.8) | |
Yes | 673 (65.1) | 298 (55.8) | 229 (72.0) | 146 (80.2) | <0.0001 |
Systolic BP, mmHg | 138 ± 18 | 136 ± 17 | 140 ± 19 | 143 ± 19 | <0.0001 |
Diastolic BP, mmHg | 76 ± 11 | 77 ± 10 | 77 ± 12 | 74 ± 10 | 0.01 |
When compared to patients with no complications, several variables were associated with multiplicity of complications. These included age, gender, education, family history, duration, and age at onset of diabetes, HbA1c level, diabetic therapy, LDL, creatinine levels, and elevated systolic blood pressure.
Table
Prevalence of major microvascular complications in 1034 patients with type 2 diabetes in Qatar, by gender.
All | Males | Females | ||
---|---|---|---|---|
1034 (100) | 798 (100) | 236 (100) | ||
<0.0001 | ||||
None | 534 (51.6) | 442 (55.4) | 92 (39.0) | |
One complication | ||||
Retinopathy | 108 (10.4) | 81 (10.2) | 27 (11.4) | 0.55 |
Nephropathy | 55 (5.3) | 50 (6.3) | 5 (2.1) | 0.01 |
Neuropathy | 155 (15.0) | 97 (12.2) | 58 (24.6) | <0.0001 |
Two complications | ||||
Retinopathy + nephropathy | 37 (3.6) | 33 (4.1) | 4 (1.7) | 0.11 |
Retinopathy + neuropathy | 79 (7.6) | 45 (5.6) | 34 (14.4) | <0.0001 |
Nephropathy + neuropathy | 24 (2.3) | 19 (2.4) | 5 (2.1) | 1.00 |
Three complications | 0.58 | |||
Retinopathy (±other complications) | 266 (25.7) | 190 (23.8) | 76 (32.2) | 0.01 |
Nephropathy (±other complications) | 158 (15.3) | 133 (16.7) | 25 (10.6) | 0.02 |
Neuropathy (±other complications) | 300 (29.0) | 192 (24.1) | 108 (45.8) | <0.0001 |
Prevalence of major microvascular complications in 1034 patients with type 2 diabetes in Qatar.
Three hundred (29.0%) patients reported neuropathy, 266 (25.7%) retinopathy, and 158 (15.3%) nephropathy. Female patients had higher prevalence of neuropathy (45.8% versus 24.1%,
The mean age at development of all three microvascular complications was similar and ranged from 53.3 ± 9.2 years (neuropathy) to 55.2 ± 10.6 years (nephropathy). Similarly, the mean interval between the diagnosis of diabetes and the development of microvascular complications was also similar, ranging from 12.9 ± 8.5 years (neuropathy) to 14.4 ± 8.1 years (retinopathy).
Table
Multivariable analysis of factors associated with microvascular complications.
Variable | Retinopathy | Nephropathy | Neuropathy | |||
---|---|---|---|---|---|---|
OR (95% CI) | OR (95% CI) | OR (95% CI) | ||||
Age (per 10 years) | 0.87 (0.69–1.11) | 0.27 | 1.18 (1.00–1.39) | 0.06 | ||
Gender (female versus male) | 1.34 (0.92–1.95) | 0.13 | 0.95 (0.53–1.70) | 0.85 | ||
Duration of DM ≥ 10 years | 1.48 (0.87–2.49) | 0.15 | ||||
Education (>high school) | 0.79 (0.57–1.10) | 0.16 | — | |||
Family history of DM (yes versus no) | — | — | ||||
HbA1c level (per % increase) | ||||||
DM treatment (insulin versus drug) | 1.26 (0.90–1.75) | 0.18 | ||||
Body mass index (per 5 kg/m2) | — | — | ||||
LDL (per mmol/L increase) | — | 0.82 (0.64–1.05) | 0.11 | — | ||
Creatinine (>106 versus ≤106 |
1.36 (0.93–1.99) | 0.12 | ||||
Hypertension or high BP | 1.31 (0.97–1.78)2 | 0.08 |
Odds ratios (OR) and 95% confidence intervals (CI) obtained from multivariable logistic regression model with all displayed variables fitted simultaneously.
This study focused on the prevalence of major complications in previously diagnosed adult male diabetics attending outpatient clinics at Hamad General Hospital that is a major provider of health care for the diabetic population of Doha, the capital of Qatar. In these adult type 2 diabetic patients, about half developed one or more microvascular complications 12–14 years after the onset of diabetes. In patients who did develop complications, about two-thirds developed a single complication and one-third developed two or more complications.
The role of smoking as an important risk factor for diabetes needs further emphasis: about half the subjects in this group of male diabetics were current or ex-smokers. The increased prevalence of smoking in these patients is understandable since smoking is known to be an important risk factor for diabetes [
In general, factors that were associated with multiplicity of microvascular complications listed in Table
HbA1c was the only factor significantly associated with all three microvascular complications, although hypertension (current or under treatment) achieved borderline significance (
This study has several weaknesses: it is cross-sectional and therefore not the best design for studying temporal changes. Although the possibility of interviewer bias exists, we believe that it should not affect our main findings since information about diabetic complications and treatment are not subjective and were corroborated with data retrieved from clinical charts. Also, participants were entirely voluntary and interviews were conducted by trained personnel. Since it is based on a clinic population, we have no information about the number of deaths or the causes of antecedent mortality, which could skew our results. As an example, smoking could be a major causative factor for deaths in this clinic population. Since this is a single institution study, the results and in particular the prevalence of complications may not be generalized; however, it was conducted in the largest tertiary care hospital in Doha, which is the most representative institution in the country. Furthermore, we report only microvascular and not macrovascular complications.
The study strengths are that the information comes from a carefully followed group of adult diabetics from a region with a high prevalence of diabetes. The Qatari and non-Qatari were similar, indicating that the findings are likely to be generalizable to the large population of male diabetics in the Middle East and perhaps to other regions. Another strength of the study is that it provides a road map to help guide diabetologists to compare and assess the likelihood of development of microvascular complications in their patients, as well as to determine the relative importance of individual risk factors for the individual type of complications.
In conclusion, this report provides information about the prevalence of individual and multiple microvascular complications among diabetics in Qatar, which has among the highest incidence rates of diabetes globally. The frequency of individual microvascular complications is generally similar to reports based on similarly aged patients from the same region [
The Office of Research at Weill Cornell Medical College-Qatar reviewed the proposal and determined that the study was exempt from Qatari and United States (US) human subjects’ protection regulations and therefore did not require review by an institutional review board (IRB number 2012-0024). The Research Committee at Hamad Medical Corporation determined that the study was exempt, according to the rules and regulations for research at Hamad Medical Corporation and allowed access to their facilities (Research proposal number 12286/12).
The authors declare that there is no conflict of interest regarding the publication of this article.
All authors have made substantive intellectual contributions to the study. Sohaila Cheema, Ravinder Mamtani, Albert B. Lowenfels, Mahmoud Zirie, Amin Jayyousi, Ziyad Mahfoud, Hekmat Alrouh, Amit Abraham, and Patrick Maisonneuve conceptualized and designed the study. Amit Abraham, Hekmat Alrouh, Sura Al-Samraye, Buthaina Ibrahim, and Ibrahim Mohammed Al-Janahi conducted the study and collected the data. Patrick Maisonneuve and Albert B. Lowenfels reviewed and analyzed the data. Sohaila Cheema, Patrick Maisonneuve, Albert B. Lowenfels, and Ravinder Mamtani prepared and formalized the manuscript. Amit Abraham, Hekmat Alrouh, Sura Al-Samraye, Mahmoud Zirie, Amin Jayyousi, Buthaina Ibrahim, Ziyad Mahfoud, and Ibrahim Mohammed Al-Janahi reviewed and edited the manuscript. All authors critically appraised, reviewed, and approved the final version of the manuscript submitted for publication.
The work was supported by the Institute for Population Health (previously Division of Global and Public Health), Weill Cornell Medicine-Qatar and Qatar Foundation, through the Weill Cornell Medicine-Qatar Biomedical Research Program.
Supplementary data include characteristics of male and female participants and analysis of factors associated with microvascular complications, adjusted for age, sex, and duration of diabetes.