Abstract and Introduction
Diabetes is among the biggest of the 21st-century global health challenges. In the U.S. and other high-income countries, thanks to investments in science, dedication to implementing these findings, and measurement of quality of care, there have been improvements in diabetes management and declines in rate of diabetes complications and mortality. This good news, however, is overshadowed by the ever-increasing absolute numbers of people with diabetes and its complications and the unprecedented growth of diabetes in low- and middle-income countries of the world. To comprehensively win the war against diabetes requires 1) concerted attention to prevention and 2) expansion of global research to better inform population-level policies to curb diabetes but also to better understand individual- and population-level variations in pathophysiology and phenotypes globally so that prevention and treatment can be tailored. For example, preliminary data show that thin people in low- and middle-income countries such as India commonly experience type 2 diabetes. Global studies comparing these thin Asian Indians with other high-risk groups such as Pima Indians, a population with a high mean BMI, suggest that type 2 diabetes may not be a single pathophysiological entity. Pima Indians may represent the well-studied phenotype of poor insulin action (type 2A), whereas Asian Indians represent the grossly understudied phenotype of poor insulin secretion (type 2B). This has major implications for diagnosis, prevention, and treatment and highlights the mismatch between where diabetes burdens occur (i.e., low- and middle-income countries) and where research happens (i.e., high-income countries). Correcting this imbalance will advance our knowledge and arsenal to win the global war against diabetes.
Type 2 diabetes is a prototypical disease at the cross-section of contemporary globalization and health. In the U.S. and other high-income countries, some successes are evident in preventing or postponing complications of the disease by better implementation of quality of care. Yet, this "winning of a battle" hides a larger worrying issue of "losing the war," stemming from the persistently high incidence of diabetes itself at home and from the expanding epidemic worldwide (Fig. 1). The war will not be won without viewing type 2 diabetes in its global context as the world becomes rapidly more interconnected in the midst of major demographic, economic, and environmental transitions. Although the majority of the disease burden resides in low- and middle-income countries, research into diabetes remains concentrated in a few high-income countries. This discrepancy between where the preponderance of the disease burden resides and where the research is conducted hampers our ability to better understand the differences in the pathophysiology, or phenotypes, of the disease. For example, studies in populations, such as Asian Indians, who have been exposed to generations of undernutrition suggest that type 2 diabetes may be highly prevalent even in thin people and may be driven not only by propensity to fat storage and insulin resistance but also primarily through innate and early problems with adequate insulin secretion. Furthermore, the etiology, clinical presentation, diagnosis, treatment, and prevention may differ by phenotypes. Studies in global settings, allowing for comparisons across populations (e.g., Asian Indians vs. Pima Indians), can better inform differences in phenotypes. It is therefore time to consider the pathophysiology of type 2 diabetes across the spectrum, from those dominantly affected by insulin resistance (type 2A) to those dominantly affected by insulin secretion (type 2B). With an increasingly interconnected world, investment in global collaboration in research and policy will be needed to win the war against diabetes.
Diabetes Care. 2016;39(5):653-663. © 2016 American Diabetes Association, Inc.