A study of thyroid function and prevalence of thyroid autoantibodies in an African diabetic population

Association between glycemic status and thyroid dysfunction in patients with type 2 diabetes mellitus

BACKGROUND

Thyroid dysfunction has been widely reported to be more common in patients with type 2 diabetes mellitus (T2DM) in various parts of the world; however, there is paucity of data on this in our environment.

OBJECTIVE

The aim of this study was to determine the possible relationship between glycemic status and thyroid dysfunction.

METHODOLOGY

A total of 354 T2DM patients and 118 non-diabetic persons (controls) were recruited for the study. A pretested questionnaire was filled for each subject after due explanations. Their blood samples were tested for HbA1c, fT3, fT4, and TSH. Information retrieved from patient's medical records included age at diagnosis of diabetes (DM) and duration of DM. Testing statistics done included Student's t-test, chi square test, and regression analysis. P-value of less than 0.05 was taken to be statistically significant.

RESULTS

The results show that 43.5% and 37.3% of T2DM and control subjects, respectively, were males. Mean HbA1c was significantly higher in T2DM patients than in the controls (7.8±2.0% vs 5.8±1.2%, p=0.001), while mean fT3 was significantly lower in T2DM patients than in the controls (2.3±1.5 pg/mL vs 2.7±2.2 pg/mL, p=0.03). Mean HbA1c was significantly higher in T2DM patients with thyroid dysfunction compared to their euthyroid counterparts (8.1±1.9% vs 5.1±1.2%, p=0.001). HbA1c had a positive linear relationship with the presence of thyroid dysfunction (regression coefficient=1.89, p=0.001).

CONCLUSION

There was a positive linear relationship between HbA1c and the presence of thyroid dysfunction in the T2DM patients in this study. There was an inverse relationship between HbA1c and serum fT3.

Frequency and determinants of thyroid autoimmunity in Ghanaian type 2 diabetes patients: a case-control study

BACKGROUND

The link between type 1 diabetes and thyroid autoimmunity is well described. The same cannot be said for type 2 diabetes where results have been mixed so far. We investigated the prevalence and determinants of thyroid autoimmunity among Ghanaian type 2 diabetes patients.

METHODS

This was a case-control study involving 302 type 2 diabetes patients and 310 non - diabetic controls aged 40-80 years. Anthropometric and blood pressure measurements were obtained. Fasting samples were analyzed for glucose, thyroid function, and antibodies to thyroglobulin and thyroid peroxidase.

RESULTS

The prevalence of thyroid autoimmunity was significantly higher among T2DM subjects (12.2% vs. 3.9%, p = 0.0004). Among T2DM subjects, 44 (14.7%) tested positive for TPOAb, 5 (1.7%) tested positive for TGAb and 15 (5.0%) tested positive for both autoantibodies. Females T2DM subjects showed a 3-fold increased risk of thyroid autoimmunity compared to males (OR:3.16, p =0.004), T2DM subjects with hyperthyroidism had a 41% increased risk of thyroid autoimmunity (OR: 1.41, p < 0.001), sub-clinical hyperthyroidism increased the risk of thyroid autoimmunity by 2 fold, (OR:2.19, p < 0.001), subclinical hypothyroidism increased the risk of autoimmunity by 4-fold, (OR:3.57 95% p < 0.0001), and hypothyroidism was associated with a 61% increased risk of thyroid autoimmunity (OR: 1.61,1.35-2.23). Dyslipidaemia was associated with a 44% increased risk of thyroid autoimmunity (OR: 1.44, p = 0.01) and a percentage increase in HbA1c was associated with 46% increased risk of thyroid autoimmunity (OR:1.46, p < 0.0001).

CONCLUSION

We observed a high prevalence of thyroid autoimmunity in Ghanaian T2DM subjects compared to the general population. Thyroid autoimmunity in T2DM subjects was significantly associated with female gender, thyroid dysfunction, dyslipidaemia and poor glycemic control.

High prevalence of antithyroid peroxidase and antiparietal cell antibodies among patients with type 1 diabetes mellitus attending a tertiary diabetes centre in South Africa

OBJECTIVE

Data on the prevalence of autoimmune thyroid disease (AITD) and gastric autoimmunity in type 1 diabetes mellitus (T1DM) in Africa are limited. The aim of this study was to assess the prevalence of antithyroid peroxidase (TPO-A) and antiparietal cell antibody (PCA) in patients with T1DM at a tertiary diabetes clinic in Durban, South Africa.

RESEARCH DESIGN AND METHODS

This was a cross-sectional observational study among subjects attending the adult T1DM clinic at Inkosi Albert Luthuli Hospital. Information about history and clinical examination was collected. Blood tests included glutamic acid decarboxylase antibody (GADA), TPO-A, PCA, vitamin B₁₂, folate, ferritin, thyroid stimulating hormone (TSH), free thyroxine, lipids and HbA1c.

RESULTS

A total of 202 (M:F, 90:112) patients were recruited. The ethnic composition was African (black) (56.4%; n=114), Indian (31.7%; n=64), white (4.5%; n=9) and coloured (mixed race) (7.4%; n=15). Mean age and mean duration of diabetes were 26.4±11.4 and 10.7±9.1 years, respectively. Mean body mass index was 21.6±6.3 kg/m². GADA was positive in 63.37% (n=128). The prevalence of TPO-A was 18.9% (n=39) and PCA 8.9% (n=17). The prevalence of overt hypothyroidism, subclinical hypothyroidism and Graves' disease was 10.9%, 2.5% and 1.5%, respectively; vitamin B₁₂ deficiency was noted in 3.5% (n=7) and iron deficiency in 19.3% (n=39).

CONCLUSIONS

Among patients with T1DM in this study, there was a high prevalence of coexistent AITD and gastric autoimmunity. Screening for hypothyroidism and thyroid autoimmunity should be undertaken in all patients at initial presentation. However, to assess the feasibility and optimal timing of subsequent testing in the African setting with limited resources, more collaborative research with longitudinal studies is required.

Thyroid Autoimmunity in the Context of Type 2 Diabetes Mellitus: Implications for Vitamin D

Vitamin D deficiency has been associated with both type 2 diabetes mellitus (T2DM) and autoimmune disorders. The association of vitamin D with T2DM and thyroid autoimmunity (TAI) has not been investigated. Thus, we aimed to explore the putative association between T2DM and thyroid autoimmunity (TAI) focusing on the role of 25-hydroxy-vitamin D (25(OH)D). Study population included 264 T2DM patients and 234 controls. To explore the potential association between 25(OH)D and thyroid autoimmunity while controlling for potential confounders-namely, age, gender, body mass index, and presence of T2DM-multivariate logistic regression analyses were undertaken. Patients with T2DM were younger (P < 0.001) and had significantly lower 25(OH)D levels (P < 0.001) and higher anti-TPO titers (P = 0.005). Multivariable logistic regression analyses suggested that T2DM and 25(OH)D levels were significantly associated with the presence of thyroid autoimmunity. In an elderly population of diabetic patients and controls with a high prevalence of vitamin D deficiency/insufficiency, a patient with T2DM was found to be 2.5 times more likely to have thyroid autoimmunity compared to a nondiabetic individual and the higher the serum 25(OH)D levels were, the higher this chance was.

Thyroid autoimmunity and function among Ugandan children and adolescents with type-1 diabetes mellitus

Introduction

Up to 30% of type-1 diabetes mellitus (T1DM) patients have co-existent thyroid autoimmunity with up to 50% of them having associated thyroid dysfunction. Routine screening for thyroid autoimmunity and dysfunction is recommended in all T1DM patients. However, this was not currently practiced in Ugandan paediatric diabetes clinics. There was also paucity of data regarding thyroid autoimmunity and dysfunction in African children and adolescents with diabetes mellitus. The objective of this study was to quantify the magnitude of thyroid autoimmunity and dysfunction in Ugandan children with TIDM.

Methods

This was a cross sectional descriptive study to determine the prevalence of thyroid autoantibodies and describe thyroid function among children and adolescents aged 1-19 years with diabetes mellitus attending the paediatric diabetes clinic at Mulago National Referral Hospital, Kampala, Uganda. Following enrollment, we obtained details of clinical history and performed physical examination. Blood (plasma) was assayed to determine levels of antibodies to thyroid peroxidase (antiTPO), free thyroxine (FT4) and thyrotropin (TSH).

Results

The prevalence of thyroid autoimmunity was 7.3% (5/69). All antiTPO positive subjects were post pubertal, aged between 13-17 years with females comprising 3/5 of the antiTPO positive subjects. All study subjects were clinically euthyroid; however, 7.3% (5/69) of the study subjects had subclinical hypothyroidism.

Conclusion

These data strengthen the argument for routine screening of all diabetic children and adolescents for thyroid autoimmunity (particularly anti-TPO) as recommended by international guidelines. We also recommend evaluation of thyroid function in diabetic children and adolescents to minimize the risk of undiagnosed thyroid dysfunction.

Diabetes and thyroid disorders

Both diabetes mellitus and thyroid disorders are common diseases. According to epidemiologic studies the prevalence of specific thyroid disorders in diabetic subjects is two times higher. Risk factors are age, female gender and autoimmune diabetes mellitus. However, thyroid disorders are diagnosed only half of the cases in diabetic population. The review briefly summarizes the association of autoimmune diabetes mellitus and thyreoiditis, the risk of thyroid disorders in type 1 diabetic pregnant women. Furthermore, the influence of obesity in the risk on thyroid cancer and the effect of glucagon-like peptide 1 analogue on thyroid medullary C-cells are discussed. Orv. Hetil., 2011, 152, 516–519.

Frequency of diabetes and thyroid autoantibodies in patients with autoimmune endocrine disease from Cameroon

BACKGROUND

Diabetes is a major cause of morbidity and mortality in both industrialized and developing countries. In Africa, there are little data on the prevalence and immunological features of patients with autoimmune endocrine diseases.

AIM OF THE STUDY

The present hospital-based study was carried out to evaluate disease-associated autoantibodies in both type 1 diabetes and thyrotoxicosis attending the Central Hospital of Yaoundee in Cameroon.

PATIENTS AND METHODS

Samples were collected from a total of 101 subjects, 47 of whom clinically had established type 1 diabetes (mean age 30.1 years +/- 7.6, mean disease duration 3.3 years), 18 had thyrotoxicosis (mean age 32.7 years +/- 7.6, mean disease duration 6.3 years +/- 2.8) and 36 normal subjects (mean age 26 years +/- 4.5). All subjects were tested for diabetes-associated glutamic acid decarboxylase (GAD) and tyrosine phosphatase (IA2) autoantibodies using antigen-specific radioimmunoassay as well as thyroiditis-associated thyroglobulin (Tg) and thyroid peroxidase (TPO) autoantibodies using commercially available kits.

RESULTS

Of 47 patients with type 1 diabetes, 16 (34%) had GAD autoantibodies (Abs), 3 (6.4%) had IA2 Abs, and 2 (4.3%) had TPO Abs. Of 18 patients with thyrotoxicosis 4 (22.2%) had GAD Abs, 5 (27.8%) showed IA2 Abs, while 8 patients (44.4%) were TPO Abs positive. No patients in either group had Tg Abs. Among normal subjects, 2 (5.6%) showed GAD Abs, and one of these was also IA2 Abs positive, but none had thyroid autoantibodies.

CONCLUSION

Adult-onset type 1 diabetic patients some years post-diagnosis from central Africa show GAD, IA2 or TPO Abs; and surprisingly, patients with thyrotoxicosis had a similar frequency of diabetes-associated autoantibodies. We conclude that, despite a different genetic and environmental background to European populations, islet cell autoimmunity is common in autoimmune endocrine patients in central Africa.

HLA-DQ polymorphisms modify the risk of thyroid autoimmunity in children with type 1 diabetes mellitus

OBJECTIVE

Type 1 diabetes mellitus (DM1) is frequently accompanied by thyroid autoimmunity (TAI). The aims of the present study were to estimate the prevalence of TAI and to determine the contribution of HLA-DQA1 and -DQB1 polymorphisms to TAI susceptibility among children with DM1. PATIENTS AND METLHODS: Screening for TAI was performed in 285 children with DM1 by measuring autoantibodies against thyroid peroxidase (anti-TPO) and thyroglobulin (anti-Tg). HLA-DQA1 and -DQB1 were genotyped using PCR-SSP.

RESULTS

Repeated positivity of anti-TPO and/or anti-Tg was found in 45/285 children with DM1 (15.8%). The prevalence was significantly higher in girls than in boys (26.7% vs 6.7%; p<10(-5)). The HLA-DQB1*0302 allele conferred susceptibility to TAI in children with DM1 (OR 2.7, 95% CI 1.1-6.4), while the DQB1*05 alleles acted protectively (OR 0.2, CI 95% 0.08-0.7).

CONCLUSIONS

HLA-DQ polymorphisms significantly modify the risk of TAI in children with DM1.

Autoimmune thyroid disease in Indian children with type 1 diabetes mellitus

The objective of the present study was to determine the prevalence of autoimmune thyroid disease in Indian children with type 1 diabetes mellitus by the assay of antibodies to thyroid peroxidase and thyroglobulin. The study population consisted of 35 children with type 1 diabetes mellitus and 32 healthy age- and sex-matched control children. Thyroid peroxidase antibodies (TPO) were determined by ELISA and thyroglobulin antibodies (TGA) by passive hemagglutination. Thyroid function tests and tests of glycemic control were also performed. These assays were repeated after six months and one year. TPO were observed in 19 (54.3%) patients compared to three (10%) controls, and TGA in 11 (31.4%) patients and none of the controls. Both these observations were statistically significant with p=0.0002 for TPO and 0.0016 for TGA. The prevalence of these antibodies was not different in boys and girls and did not change with the duration of diabetes. All patients who were positive for TGA were also positive for TPO. Thyroid function tests were abnormal in one patient who was found to have Hashimoto's thyroiditis. There is a definite need to screen all diabetic children for thyroid antibodies and carefully follow up those patients in whom these antibodies are positive.