Measurement of insulin action: a tribute to Sir Harold Himsworth

Sir Harold Himsworth was a renowned clinician and researcher. Among his myriad of accomplishments, he was the first to differentiate diabetes mellitus into insulin-sensitive and insulin-insensitive forms. To help distinguish these two types, he developed the first test to measure insulin sensitivity, the insulinglucose test. This article reviews Himsworths pioneer methods and subsequent advances in the measurement of insulin action. The advantages and limitations of commonly used methods to assess insulin sensitivity are also examined.