Effects of experimental hypothyroidism on insulin, glucose tolerance test and pancreatic tissue in adult male rats

Hypothyroidism and diabetes mellitus are two incident human diseases that occur simultaneously in frequent cases. There are conflicting reports regarding hypothyroid effect on blood glucose and insulin levels. In the present study by caring glucose tolerance test, measuring fasting insulin level and assessing histological alterations in Langerhans islets of experimentally hypothyroid rats, we investigated if hypothyroidism can induce diabetes mellitus?

In the present study, twenty male wistar rats were divided into two groups of control and hypothyroid. In order to induce hypothyroidism, this group was drank tap water containing 0.02% PTU (propylthiouracil) and the control group was given tap water. At five weeks of experiment glucose tolerance test was performed and three weeks later blood samples were prepared for T4, T3, TSH and Insulin hormones measurement. The pancreas tissue then extracted for histological assessment.

Our results indicate that 5 week consumption of 0.02% PTU does not affect glucose tolerance test significantly while 8 week consumption decrease hormones levels of T3, T4 and insulin and increase TSH significantly (p<0.01). Histological findings show no changes in Langerhans architecture in hypothyroid rats contrast to control group.

Based on our findings we can conclude that hypothyroid disease through unknown mechanism decreases insulin level significantly and it can lead to histological changes in Langerhans islets and consequently to prevalence of diabetes mellitus.