Thyroid Dysfunction In Type 2 Diabetes: An Epidemiological Assessment Of Prevalence And Association In An Algiers Center Cohort

Abstract

OBJECTIVES: The aim of this study was to estimate the prevalence of thyroid dysfunction, to investigate the association between the two pathologies, and to identify associated risk factors in patients with type 2 diabetes.

METHODS: A cross-sectional study conducted in the diabetology department of the Central Hospital of Algeria in Algiers, between 2024 and 2025. Out of a total of 380 patients with Type 2 Diabetes (T2D) identified within the department, 100 patients were included in this epidemiological study, as they satisfied all selection criteria, notably the availability of thyroid function tests. The final included sample thus represents 26.3% of the identified T2D population. The remaining 280 patients were excluded from this specific analysis and will be considered for a subsequent study. Demographic, clinical, biological, and hormonal data (Glycemia, HBA1c, TSH and total hemoglobin) were collected, and the risk factors associated with thyroid disorders were assessed by comparing diabetic patients according to their thyroid status. The statistical analysis was performed using SPSS version 26 software, with the level of significance set at p < 0.05.

RESULTS: The mean age of the patients was 56 .13 ± 13,65 years, with 56 % of the cohort being male. The overall prevalence of thyroid disorders among patients with Type 2 Diabetes (T2D) was 26.31%. The majority of the cohort (75%) was euthyroid, while the remaining 25% presented with hypothyroidism. It is noteworthy that no cases of hyperthyroidism were observed. Regarding metabolic control, the mean fasting blood glucose (FBG) level was marginally higher in hypothyroid patients (1.72 ± 0.86 g/L) compared to euthyroid patients (1.55 ± 0.67 g/L); however, this difference did not reach statistical significance (p = 0.461). 

In contrast, hypothyroidism was significantly more prevalent in patients with uncontrolled diabetes (36.7%) than in those with controlled HbA1c (13.7%), establishing a highly significant association between the two variables (χ² = 7.05; p = 0.008). 

Further analysis showed that hypothyroid patients exhibited a significantly longer duration of diabetes (17.0 ± 10.42 years) compared to euthyroid patients (9.85 ± 6.07 years). This difference was highly significant (p = 0.002), underscoring a strong association between the duration of diabetes and hypothyroidism. Furthermore, hypothyroidism was significantly associated with diet: it was observed in 35.3% of patients reporting an unbalanced diet, compared to only 14.3% in those with a balanced diet (χ² = 5.88; p = 0.015).

Conversely, no statistically significant association was found between thyroid status and the presence of either hypertension or dyslipidemia, nor with the presence of microvascular or macrovascular complications.

Finally, while univariate analysis revealed a marked female predominance and an increased frequency of thyroid disorders in older individuals, those with a sedentary lifestyle, and those using certain types of treatment, only a sedentary lifestyle proved to be an independent risk factor in our population. This suggests a potential primary role of lifestyle in the occurrence of these disorders. 

CONCLUSIONS: Hypothyroidism exhibits a significant prevalence in T2DM patients and is strongly associated with poor glycemic control and a long duration of diabetes. Crucially, no significant association was found between thyroid status and the presence of micro- or macrovascular complications. Sedentary lifestyle was identified as the sole independent risk factor for thyroid dysfunction. These findings underscore the need for targeted screening (especially among women and sedentary individuals) and the crucial importance of lifestyle modifications for the prevention of this comorbidity.