What Causes Drowsiness And Weakness While Having High Blood Sugar Levels?

Hello Dr. I am regularly taking medicines for control of blood sugar. Fasting 104 PP 145 . Dr has prescribed Glycomet GP1500mg one tab before breakfast and Glycomet SR 500 after dinner one tab each. I am feeling drowsiness and feel weak after taking these medicines. I am also a patient of Acetabulum . My left femur bone have been dislocated due to a road accident in the year 1999 June 29th. Since then I am having much pain while walking. Still I walk for 1.1 Km during evening. My question is how can I control blood sugar although I donot take heavy diet and take only veg soup and veg curry with two chapatti and a glass of milk during supper. Light lunch with little rice dal and veg curry. No spicy food nor non veg food .