Association between continuity of care and type 2 diabetes development among patients with thyroid disorder

Thyroid disorders are associated with blood glucose abnormalities. For rendering the patients euthyroid, routine screening and care are essential. Therefore, the aim of this study was to investigate the association between continuity of care (COC) and type 2 diabetes onset among patients with thyroid disorders. We used the national claim data. Our study population was 4099 patients with hyperthyroidism or hypothyroidism. For calculating COC, the Most Frequent Provider Continuity Index (MFPCI), Modified Modified Continuity Index (MMCI), and COC Index (COCI) were used. The dependent variable was type 2 diabetes onset. The Cox proportional hazard regression model was used. Among 4099 patients with thyroid disorders, 25.3% experienced onset of type 2 diabetes. Thyroid patients who had MFPCI and COCI below the median were more likely to experience onset of type 2 diabetes than who had these indices above the median (MFPCI: hazard ratio [HR] = 1.26, 95% confidence interval [CI] = 1.09–1.46; COCI: HR = 1.22, 95% CI = 1.06–1.41). Our subgroup analysis showed that female patients and those 20 to 34 years of age showed a significant association between COC and onset of type 2 diabetes. Patients with thyroid disorders with low COC showed an increased risk of developing type 2 diabetes. Therefore, efforts to enhance COC among patients with thyroid disorders needs to be encouraged.