Monitoring glycaemic control in patients with diabetes mellitus

### What you need to know A 73 year old man with obesity and type 2 diabetes mellitus was referred to the diabetes clinic for advice. He had chronic kidney disease stage 3 and chronic anaemia from angiodysplasia of the small intestine. He was on insulin glargine 35 units every night and soluble human insulin 30 units three times daily before main meals. He was referred because of the discrepancy between his high fasting plasma glucose concentrations (16-21 mmol/L) and lower than expected haemoglobin A1c (HbA1c) concentration (49 mmol/mol) (expected with this fasting plasma glucose concentration ~108-140 mmol/mol or 12-15%). Table 1 gives glucose and HbA1c reference intervals. Other selected blood tests were: haemoglobin 106 g/L (reference interval: 125-180), ferritin 315 µg/L (reference interval: 24-250), creatinine 107 µmol/L (reference interval: 59-104), and albumin 32 g/L (reference interval: 35-50). View this table: Table 1 Reference interval for fasting glucose and HbA1c ### Monitoring diabetes mellitus The diagnosis of diabetes mellitus is well described1234; however, the monitoring of diabetes with HbA1c (which is common practice) has introduced some uncertainty. Glycaemic control is integral to effective treatment of diabetes.12 HbA1c concentration is used as the biomarker for long term glycaemic control as it correlates well with average blood glucose levels over a period of 90-120 days …