Diabetes mellitus is a chronic major endocrine disorder and growing health problem in most countries and is characterized by hyperglycemia, hyperlipidemia, negative nitrogen balance and sometimes ketonemia. Diabetes is one of stress-related disorders. Diabetic subjects are shown to have increased oxidative stress and decreased antioxidant levels. Antioxidants are claimed to work as antistress agents by decreasing oxidative stress. Lycopene, a carotenoid is mostly found in tomatoes and tomato products. It is a powerful antioxidant with a single-oxygen quenching capacity. It is 100 times greater than that of ¿-carotene and vitamin-E respectively. This book defining the alteration in the effectiveness or toxicity of one drug due to another simultaneously administered drug is known as drug-drug interaction. A drug interaction may result in adverse effects wherein there is a decrease in the effectiveness. Biological interference with laboratory tests may mislead the diagnosis. Beneficial effects, wherein there is an increase in the effectiveness or a decrease in the toxicity of one drug in the presence of another.