Type 2 Diabetes in Youth: Epidemiology and Pathophysiology

The prevalence of type 2 diabetes is significantly increased in the pediatric population, which is affected by obesity worldwide. The progression from normal glucose tolerance (NGT) to type 2 diabetes involves intermediate stages of impaired fasting glucose (IFG) and impaired glucose tolerance (IGT), also known as prediabetes. The pathophysiology underlying the development of these glucose metabolic alterations is multifactorial; however an alteration in the balance between insulin sensitivity and insulin secretion represents the most important player in the development of type 2 diabetes. Obese children and adolescents affected by IGT and type 2 diabetes are characterized by severe insulin resistance, which is associated with an increased lipid accumulation in visceral compartments, liver and muscle tissues and by reduced sensitivity of I²-cell of first and second-phase insulin secretion. The progression in obese children of insulin resistance to type 2 diabetes has been shown to be faster than in adults; in addition, type 2 diabetes is already associated with several metabolic and cardiovascular complications in this age group. In the present review, we summarize the most recent findings concerning the prevalence of type 2 diabetes in youth and in particular we explore the pathophysiology of type 2 diabetes and the natural history of this pathology in obese children and adolescents. Concurrent with the worldwide epidemic increase of childhood obesity, type 2 diabetes and the two prediabetic conditions, IFG and IGT, are becoming increasingly more common in obese children and adolescents (1,2). Until 10 years ago, type 2 diabetes accounted for less than 3% of all cases of new-onset diabetes in adolescents. At present 45% of cases are attributed to it (3,4). Type 2 diabetes occurs in youth more often during the second decade of life, coinciding with the physiological occurrence of pubertal insulin resistance (1). In addition, …