In this systematic review, we explored the effects of physical activity, diet, and lifestyle on the prevention of diabetes mellitus in Nigeria. Diabetes is an autoimmune disease which occurs when the body does not produce or respond properly to insulin, a hormone essential for daily life. Diabetes is an incurable disease, which has no racial, social, or sex barrier. The risk factors include a poor diet, lack of physical activity, obesity, and an unhealthy lifestyle. About 100 million people in the United States have diabetes mellitus, and the total economic costs of diabetes exceed USD 132 billion a year. Diabetes accounts for 1 of every 10th USD spent on health care in the United States, and an estimated 48 million Americans may develop diabetes by 2050. However, it is estimated that in 90% of the patients with type 2 diabetes the disease could be prevented if people adopted a healthy lifestyle, including regular physical activity, a moderate-good diet, and modest weight. Because of the deleterious health consequences which include blindness; kidney damage; cardiovascular disease; and reduced life span, as well as high treatment costs, prevention of the disease in Nigeria, where you are confronted with a poor health care system, poverty, and ignorance, but also have ample opportunities for physical activity and rich local nutrients to supply an ideal diet, is a viable option. Consequent upon this, the paper recommends, among others, that available local resources be used for this purpose.