Metabolism of thyroid hormones is influenced by acute systemic illnesses including diabetic ketoacidosis. In these cases T3 level is usually decreased and this condition is called “low T3 syndrome” which is usually reversed by treating the under lying Disease.thyroid function test analysis before and after diabetic ketoacidosis treatment.In this cross sectional study thyroid function tests were analyzed in 16 diabetic ketoacidosis patients according to American diabetic association before and after insulin therapy.mean triiodothyronine (T3) level before and after ketoacidosis treatment were 63.2±28.2ng/dl/and 78.5±26.2ng/dl (P. value 0.00) respectively and the mean thyroxin level (T4) before and after ketoacidosis were 3.18±1.4ng/dl and 5.17±2.4ng/dl (P. value=0.00) .Mean thyrotropin (TSH) level and triiodothyronine uptake (T3RU) before and after treatment showed no significant difference.Diabetic ketoacidosis is a sever systemic disease which along with reduction in T3 level, T4 level is also decreased and TSH level is normal. The changes in Thyroid hormones are reversed to normal after treatment of ketoacidosis so it is recommended in interpreting results of TFT in these patients we should consider these facts and thyroid function test should be repeated after treatment.