Background Type 2 Diabetes Mellitus is a common metabolic disease characterized by a decline in insulin sensitivity and relative insulin insufficiency-induced hyperglycemia. In type 2 diabetic patients who have failed to achieve target glycemic control goals on oral anti-diabetic drug therapy, Initiating insulin therapy significantly improved overall glycemic control. Objective To assess Impact of Initiation of Insulin Therapy on Serum Prolactin and Cortisol levels In Type 2 Diabetic Male Patients. Subjects and Methods It was conducted on thirty (30) male patients who were diagnosed to have type 2 diabetes attending diabetes clinic at Ain- Shams University Hospital from 1 Jan. to 1 July 2018. Their ages range from 40 to 60 years old. Results On studying the Correlation between cortisol and prolactin with other laboratory findings showed that: There were no significant correlations between cortisol a.m. and prolactin with FBS, 2HPPBG and HbA1C (P > 0.05) in the first and third visits in group I. And no significant correlations between cortisol a.m. and prolactin with FBS and 2HPPBG (P > 0.05) in the second visit in group I. But there was a significant positive correlation between cortisol with FBS (P = 0.028) and HbA1C (P = 0.033) in group II. And a significant positive correlation between cortisol with FBS (P = 0.034) and 2HPPBG (P = 0.041) in group III. There was a highly significant positive correlation between cortisol and FBS (P = 0.001) in group III. And there was a highly significant positive correlation between prolactin with 2HPPBG (P = 0.008) in group II. Conclusion We conclude from this study that initiation of insulin therapy in poorly controlled diabetic patients achieves a highly significant reduction in blood glucose level. Also, insulin therapy in diabetic patients has impact on other hormones regulating blood glucose level as it reduces serum prolactin and cortisol levels. Also we conclude that prolactin is a diabetogenic hormone.