Nearly half (47%) of the global population has limited or no access to key tests and services that are essential for diagnosing common diseases, such as diabetes, hypertension, HIV, and tuberculosis, or basic tests for pregnant women such as hepatitis B and syphilis, according to new analysis. Without access to accurate, high-quality, and affordable diagnostics, many people will be overtreated, undertreated or not treated at all, or exposed to unnecessary and potentially harmful treatment.