Thyroid dysfunction in type 2 diabetes

ABSTRACT

The association between diabetes mellitus and thyroid disorders was always a matter of medical interest. The explanation of that association is still debatable whether through metabolic, immune, vascular or multifactorial. The aim of the present study was to identify subjects at risk of clinical or subclinical thyroid dysfunction by other investigation modalities in diabetics. Forty seven type 2 diabetic patients 21 men and 26 women with age xx ranging from 40-70 years and 20, age, sex and weight matched healthy control subjects were subjected to estimation of fasting, postprandial plasma glucose. Estimation of serum free T3 and T4 and TSH by radioimmunoassay. Thyroid scan dynamic and static using technetium[99m]. Thyroid colour coded duplex Doppler study of the inferior thyroid arteries. Exclusion criteria included drugs that interfere with thyroid functions. As regards Technetium thyroid scan the perfusion index [PERI] was significantly higher in patients compared to control subjects [p-value < 0.009]. A negative correlation was found between the duration of DM and the functional index which was statistically significant in diabetic women [r = -0.4264, p=0.03]. Thirty percent of patients were detected to have dynamic thyroid scan characteristics of thyroiditis with marked increase of the perfusion index, marked decrease of the functional index till zero and replacement of slope II and III with a plateau. As regard duplex Doppler Results: the mean pulsatility [PI] and resistivity [RI] indices were found to be higher in patients with thyroiditis [as evident by thyroid scan]. The peak systolic, diastolic, end diastolic and mean velocities where statistically lower in those patients compared to control. The mean value of pulsatility and resistivity indices were significantly higher in patients with subclinical hypothyroid state than control subjects, whereas, thyroid gland volume, blood flow and blood velocities showed no statistically significant difference. Tc[99m] dynamic thyroid scan and duplex Doppler sonography detected hypofunction and abnormal perfusion while the thyroid hormones were still on the low normal side. So, it is recommended to use these investigation tools in following up patients with long standing diabetes specially in those who show clinical or laboratory evidence of thyroiditis, [such as neck pain, thyroid swelling or elevated ESR]. A condition which is not uncommon in patients with Type 2 diabetes