Prevalence of low serum testosterone levels among men with type 2 diabetes mellitus attending two outpatient diabetes clinics in Durban, South Africa.
Paruk, Imran Mahomed.
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Background: Studies showing a high prevalence of low serum testosterone in men with type 2 diabetes mellitus (T2DM) are well documented but evidence from sub-Saharan Africa is scanty. Aim: To determine the prevalence and associated risk factors of low serum testosterone and the prevalence of androgen deficiency symptoms in South African men with T2DM. Methods: A cross-sectional observational study was performed among men with T2DM attending two outpatient adult diabetes clinics in KwaZulu-Natal. Androgen deficiency symptoms were assessed using the Ageing Male’s Symptom Scale (AMS) questionnaire and direct enquiry. Serum total testosterone (TT), sex-hormone binding globulin (SHBG), luteinising hormone (LH), HbA1c, fructosamine, serum lipids were measured and free-testosterone (FT) was calculated. TT, SHBG and FT levels were measured in control subjects with no history of diabetes. Results: The study included 148 men with T2DM (Study Group) and 50 control subjects (Control Group). The mean age of the control group was 43.9 ± 10.7 years and the mean BMI was 27.11 ± 4.2 kg/m2. In the study group, the majority were African (Black) (58.7%); Indians (39.2%) and Whites (2.1%) constituted the remainder. Mean age was 57.5 ± 11.2 years; mean duration of diabetes 11.4 ± 8.9 years; mean HbA1c was 8.6 ± 1.9%. Metabolic syndrome was found in 86.4% (n:127) of the Study group. Mean TT, SHBG, FT and median LH (IQR) in the Study group were within normal range (14.5 ± 5.8 nmol/l, 40.7 ± 20.3 nmol/l, 265.9 ± 90.4 pmol/l and 5.3 [3.8-7.3] IU/l, respectively). However, mean serum TT and FT was lower in the Study group than Control subjects (14.5 ± 5.8 vs. 18.8 ± 7.2 nmol/l, p <0.001 and 265.9 ± 90.4 vs. 351.7 ± 127.3 pmol/l, p<0.001). The prevalence of LSTT and LSFT was 35.8% and 16.2%, respectively. Prevalence of LSFT increased with age and higher body mass index (BMI) categories with the highest rate noted in >40 kg/m2 BMI category (50%). In multivariate analysis, LSFT was significantly associated with age [OR 1.05 (95% CI 1.02-1.218), p=0.043] and waist circumference (WC) [OR 1.033 (95% CI 0.999- 1.068), p=0.059]. LSTT was associated with BMI only [OR 1.138 (95%CI 1.063- 1.218), p<0.0001]. TT correlated inversely with BMI, WC and the number of metabolic syndrome criteria. FT correlated inversely with BMI, WC and WHR. For both FT and TT, no significant correlation was observed with HbA1c. The prevalence of androgen deficiency symptoms using AMS score was 74.5%. The prevalence of any androgen deficiency symptom on direct enquiry was 68.9%. The AMS score correlated poorly with LSTT or LSFT and was not superior to direct enquiry. Conclusion: In this group of predominantly African and Indian men with T2DM from KwaZulu-Natal, there was a high prevalence of LSTT and LSFT. Serum TT and FT was lower in men with T2DM compared to control subjects. Waist circumference was a significant risk factor associated with LSFT while LSTT was associated with higher BMI and older age. There was a high prevalence of androgen deficiency symptoms using both the AMS score and on direct enquiry. The AMS score was a poor predictor of low testosterone and was not superior to direct enquiry. More research is required locally and from other sub-Saharan African countries before routine screening can be recommended.