This study investigated CGM accuracy within the hypoglycaemic range in three different clinical settings of hypoglycaemia.<h4>Materials and methods</h4>Ninety-two people with various causes of hypoglycaemia were analysed: (i) people during insulin tolerance testing (ITT) (n = 63); (ii) people with insulinoma (n = 16); and (iii) people with diabetes receiving subcutaneous insulin therapy (n = 13). The gene discussed is INS; the disease is pancreatic insulinoma.