Association among subclinical hypothyroidism, TSH levels and microvascular complications in Type 2 diabetic patients

Abstract

Aims: To determine whether there is an association among subclinical hypothyroidism, upper normal TSH values and microvascular complications in Type 2 diabetes. Patients and methods: 194 Type 2 diabetic patients who were hospitalized in the Endocrinology ward of Wuhan Union Hospital, were subjected to thyroid function test ( FT3, FT4, TSH) and were screened for microvascular complications of diabetes (retinopathy, nephropathy, neuropathy). Results: Apart from TSH levels, no significant differences were found in the clinical characteristics between the subclinical hypothyroidism and euthyroid groups. No significant difference was found in the prevalence of retinopathy, nephropathy and neuropathy in the euthyroid and subclinical hypothyroidism group (P>0.05). After adjustment for potential confounding factors (age, HbA1c, duration of diabetes, gender, presence of hypertension), subclinical hypothyroidism was still not associated with retinopathy (OR 0.753, 95 % CI 0.203 - 2.793, P = 0.671), nephropathy (OR 1.312, 95 % CI 0.304 - 5.659, P = 0.716) and neuropathy (OR 0.591, 95 % CI 0.156 - 2.232, P = 0.428). The prevalence of microvascular complications were similar in euthyroid type 2 diabetic patients with TSH values in the upper normal range (TSH 2.00 - 4.94 µIU/ml) and in those with lower TSH values (TSH 0.35 - 1.99 µIU/ml), (P>0.05). There was no significant difference in the TSH levels of the patients who had any particular microvascular complication or a combination of them (P = 0.827). Conclusion: We conclude that there is no association among subclinical hypothyroidism, upper normal TSH