05-Rezvani

JRHS 2012; 12(2): 98-100

Copyright © Journal of Research in Health Sciences

Comparison of Serum Free Testosterone, Luteinizing Hormone and Follicle Stimulating Hormone Levels in Diabetics and Non-Diabetics Men- a Case-Control Study

Mohammad Reza Rezvani (MD)a, Seyed Alireza Saadatjoo (MSc)b, Shahabaddin Sorouri (MD)c and Mohammad Hassanpour Fard (PhD)d*

aDepartment of Internal Medicine, Valye-Asr Hospital, Birjand University of Medical Sciences, Birjand, Iran

b Diabetes Research Center, Faculty of Nursing and Midwifery, Birjand University of Medical Sciences, Birjand, Iran

c School of Medicine, Birjand University of Medical Sciences, Birjand, Iran

d Department of Pharmacology, School of Medicine, Birjand University of Medical Sciences, Birjand, Iran

* Correspondence:Mohammad Hassanpour Fard (PhD), E-mail: mhassanpour61@yahoo.com

Received: 27 August 2012, Revised: 09 October 2012, Accepted: 09 November 2012, Available online: 28 November 2012

Abstract

Background: Diabetic men have been claimed to have lower serum free testosterone (FT) concentrations than non-diabetic men. The aim of this study was to investigate if serum FT, luteinizing hormone (LH), and follicle stimulating hormone (FSH) concentrations are different in patients with type 2 diabetes mellitus compared with healthy men and to identify factors associated with low serum testosterone concentrations in men with type 2 diabetes.

Methods:  Serum FT, LH and FSH concentrations in 65 men with type 2 diabetes between 50 and 55 years compared with 65 non-diabetic men in Valye-Asr Hospital in Birjand, Iran during October 2009 to August 2010. In addition, the relationships between serum FT concentrations with LH and FSH concentrations as well as other factors including age, fast blood sugar and glycemic control (HbA1C) were investigated.

Results:  Serum FT concentrations were significantly lower in type 2 diabetic patients (2.53±1.68 pg/ml) than in healthy men (4.29±2.43 pg/ml) (P < 0.001). There were not any significant differences in LH and FSH concentrations between the two groups. There was a significant negative relationship between serum FT and HbA1C, but this relation for LH and FSH was positive and non-significant (P < 0.001).

Conclusion:  Serum FT concentration is lower in type 2 diabetic patients compared with non-diabetic men suggesting further research to better understand the underlying biologic mechanisms.

Keywords:Diabetes Mellitus, Testosterone, Luteinizing Hormone, Follicle Stimulating Hormone

Introduction

Diabetic men have significantly lower concentrations of free and total testosterone than non-diabetic men 1,2. Hypogonadism has also been reported in men with type 2 diabetes 3, 4. Furthermore, results from the Massachusetts Male Aging Study and others suggest that low concentrations of endogenous androgens such as testosterone had been related to the development of insulin resistance, which is an important cause for inducing type 2 diabetes and other abnormalities including hyperglycemia, hypertension, dyslipidemia, or carotid atherosclerosis 5-8.

However, a recent study showed that men with higher estradiol levels had an increased risk of later diabetes independent of obesity, while men with lower total testosterone and sex hormonebinding globulin (SHBG) had an increased risk of diabetes that appeared to be dependent on obesity 9.

In the present study, we evaluated whether free testosterone (FT) concentrations are lower in patients with type 2 diabetes in comparison to healthy men and to find the relationships between follicle stimulating hormone (FSH) and luteinizing hormone (LH) in diabetic and non-diabetic men. Moreover, we investigated the correlations among fasting blood sugar (FBS), LH, FSH, glycemic control (HbA1C) and FT in men with type 2 diabetes.  

Methods

This case-control study was conducted at the Diabetic Clinic of Valy-Asr hospital in Birjand City (Iran) during October 2009 to August 2010. Sixty-five male type 2 diabetes mellitus patients from 50 to 55 years were selected from patients who had attended to the diabetic special clinic. Inclusion criteria for diabetic patients were the level of 10-12 hours fasting blood sugar (FBS) > 126 mg/dl or random FBS > 200 mg/dl along with diabetic symptoms and/or two hours glucose tolerance test more than 200 mg/dl. Patients with a known history of hypogonadism, panhypopituitarism, coronary heart disease (CHD) or chronic debilitating disease, such as HIV, cirrhosis, renal failure, and/or patients who had used medicines that influence hormones such as corticosteroids, androgens etc were excluded from the study. Control group were sixty-five subjects without history of diabetes mellitus whose FBS were less than 126 mg/dl on two occasions and were matched for age and as well as exclusion criteria of diabetic patients. Informed consent was obtained from all participants, and the study was approved by the BUMS Research Ethics Committee.

Ten ml of venous blood of all subjects was collected and centrifuged. The serums of samples were separated and frozen till performing the experiments. Quantitative determination of serum FT was measured by competitive enzyme immunoassay test using kit (IBL, code no. DB52181, Italy). The intra-assay coefficients of variance (CV) were 17.0, 4.9 and 4.7%, for FT concentrations of 1.17, 15.96 and 62.46 pg/ml, respectively. Serum LH and FSH concentrations were measured by a microplate immunoenzymometric assay using kits from (Costa mesa, code no. 625-300, CA, 92627, USA) and (Costa mesa, code no. 425-300, CA, 92627, USA) respectively. The intra-assay CVs were 5.4, 4.2 and 4.8% for LH of 2.8, 15.2 and 48.5 mlU/ml, respectively. They were 4.3, 4.3 and 2.9% for FSH of 5.9, 16.0 and 41.3 mlU/ml, respectively. HbA1C was measured by Research Center Lab of BUMS using latex immunoturbidimetric assay (LIA). This method utilizes the interaction of antigen and antibody to directly determine the HbA1C in whole blood. The intra-assay CVs were 1.43 and 1.72%, for HbA1C of 5.48 and 10.28 U/L, respectively.

Statistical analysis

The data are presented as means ± standard deviation (SD). Independent T and Chi-Square tests were used to compare relative frequency of abnormal FT concentrations in diabetic and non-diabetic patients. The relationships of age, FBS, FSH, LH, HbA1C and FT in the diabetic patients were evaluated by Pearson correlation test. P-value less than 0.05 were considered statistically significant. All statistical analysis was performed using statistical package of SPSS 11.

Results

Mean of age in diabetic patients was 52.95±1.69 years and in non-diabetic 53.22±1.61 years (P=0.701). FBS in diabetic subjects (198.95±63.80 mg/dl) was significantly higher compared to that of non-diabetic subjects (90.94±14.97mg/dl) (P=0.033). Mean FT concentrations in diabetic men were significantly lower in comparison to non-diabetic men (P<0.001) but there was no significant difference between two groups in the means of LH and FSH (Table 1). In diabetic patients mean FT concentrations were significantly higher in patients with HbA1c < 8.0% compared to patients with HbA1c >8.0% (3.29±1.83 vs. 2.28±1.57) (P=0.042) and there was also a significant relationship between the level of HbA1c and FBS concentration (r=0.44, P<0.001) (Table 2).

In 53 (81.5%) diabetic men and 32 (49.2%) non-diabetic men, FT concentrations were under the normal rate (<3.84 pg/ml) (P=0.001). The results also showed that there was a significant negative relationship between serum FT and HbA1C, but this relation for LH and FSH was positive and non-significant. The relationship between age, FBS, LH, FSH, HbA1C and FT in diabetic patients has shown in Table 3.

Table 1: Comparison of the mean of luteinizing hormone (LH), follicle stimulating hormone (FSH), and free testosterone (FT) concentrations in the serum of diabetic and non-diabetic subjects

Table 2: Comparison of the means of fasting blood sugar (FBS) and free testosterone (FT) with respect to HbA1C level 8 (N=16) and HbA1C level >8 in diabetic patients  

Table 3: Correlation between age, fasting blood sugar (FBS), luteinizing hormone (LH), follicle stimulating hormone (FSH), free testosterone (FT) and HbA1C in diabetic patients

Discussion

The present patient-based study shows that serum FT concentrations were significantly (P<0.001) lower in male patients with type 2 diabetes in comparison to healthy men. However, there were no significant differences between LH and FSH in diabetic men compared to healthy men.

A previous study among 38 young (aged 18-35 years) type 1 diabetic and 24 type 2 diabetic patients showed that type 2 diabetic men had significantly lower serum total and FT concentrations and inappropriately low LH and FSH concentrations with high prevalence of hypogonadotrophic hypogonadism in comparison with type 1 diabetic subjects 10. Their group had previously shown that type 2 diabetic patients with a mean age of 55 years had a frequent occurrence of hypogonadotrophic hypogonadism, as reflected in low plasma concentrations of testosterone and inappropriately low LH and FSH. In the present study, we did not determine the relationship between FT and LH but, Ando et al. 1984 and Fukui et al. 2007 had demonstrated a negative correlation between FT and LH 11, 12. Other studies carried out in middle-aged populations, had also confirmed the occurrence of hypogonadotrophic hypogonadism due to low plasma concentrations of testosterone, LH and FSH 13, 14. We tested serum FT concentration instead of total testosterone concentration in healthy men and patients with type 2 diabetic. FT concentration had a stronger correlation with the presence of diabetes mellitus than total testosterone concentration because FT concentration is a more sensitive and active marker for insulin resistance or atherosclerosis 15. In a large population-based cohort, Schipf et al. showed that there was an association between total testosterone and incidence of type 2 diabetes mellitus. Their prospective findings suggest the importance of measuring total testosterone in men as the predominant male sex hormone 16

Low levels of sex hormonebinding globulin (SHBG) and total testosterone in men may be involved in the pathogenesis of type 2 diabetes in humans. In a 9-month lifestyle intervention research on 225 subjects the levels of SHBG were positively correlated with insulin sensitivity, independently of sex, age and total body fat 17. They concluded that possible mechanisms by which high circulating SHBG prevents the development of type 2 diabetes involve regulation of fasting glycemia but not alteration of insulin secretory function 17.

In another study on 1709 men that evaluated for 7-17 years, SHBG was an independent predictor of incident type 2 diabetes mellitus even after adjusting for FT or total T 18. Bedsides, FT was not significantly associated with type 2 diabetes mellitus. SHBG may contribute to the risk of type 2 diabetes through nonandrogenic mechanisms, which should be investigated as they may provide novel targets for diabetes prevention 19. Although we did not evaluate the level of SHBG in subjects, but the serum FT concentration was significantly lower in type 2 diabetic patients compared to that of healthy men and it can be used as a marker of men patients with type 2 diabetes.

There was a significant negative correlation between testis weight and fasting blood sugar, moreover in male diabetic rats, with a variety of hypogonadisms such as atrophy of testis and low sperm count, FT, LH and SHBG were normally preserved 20.

Conclusion

Serum free testosterone is lower in type 2 diabetic patients compared with non-diabetic men and there is also a negative correlation between FT and HbA1C in men with type 2 diabetes. This finding suggests further research to better understand the underlying biologic mechanisms.

Acknowledgments

The authors acknowledge the laboratory staff of research center of BUMS for helping us in performing the experiments.

Conflict of interest statement

There is no conflict of interest in this article.

Funding

The present research was funded by Birjand University of Medical Sciences.

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