One study used self-reported data28 and three studies used a combination of hospital records and self-reported data.29–31 The outcomes included diabetes and pre-diabetes prevalence and incidence (n=19), levels of fasting blood glucose (FBG) (n=11), 2-hour plasma glucose (n=1), glycated haemoglobin (HbA1c) (n=5), insulin level (n=1) and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) (n=1). Here, INS is linked to diabetes mellitus.