β-cell dysfunction: Its critical role in prevention and management of type 2 diabetes

Type 2 diabetes (T2DM) is characterized by insulin resistance and beta-cell dysfunction. Although, in contrast to type 1 diabetes, insulin resistance is assumed to be a major pathophysiological feature of T2DM, T2DM never develops unless beta-cells fail to compensate insulin resistance. Recent studies have revealed that a deficit of beta-cell functional mass is an essential component of the pathophysiology of T2DM, implying that beta-cell deficit is a common feature of both type 1 and type 2 diabetes. beta-cell dysfunction is present at the diagnosis of T2DM and progressively worsens with disease duration. beta-cell dysfunction is associated with worsening of glycemic control and treatment failure; thus, it is important to preserve or recover beta-cell functional mass in the management of T2DM. Since beta-cell regenerative capacity appears somewhat limited in humans, reducing beta-cell workload appears to be the most effective way to preserve beta-cell functional mass to date, underpinning the importance of lifestyle modification and weight loss for the treatment and prevention of T2DM. This review summarizes the current knowledge on beta-cell functional mass in T2DM and discusses the treatment strategy for T2DM.