The use of point-of-care blood ketone monitors in the management of diabetic ketoacidosis in adults.

Abstract

Diabetic ketoacidosis (DKA) is the hallmark of absolute insulin deficiency, occurring predominantly in people with type 1 diabetes. It is a major cause of diabetes-related morbidity. Glucose is unable to enter cells on account of the lack of insulin, with consequent hyperglycaemia. At the same time, there is an increase in lipolysis (release of free fatty acids from adipose tissue), another process controlled by insulin. The free fatty acids are converted into ketone bodies – mainly acetoacetate and -hydroxybutyrate – to form alternative energy substrates. For many years, there was no formal way to diagnose DKA other than by measuring blood glucose concentrations and dipping the urine to check for the presence of ketones. In addition, the presence of a metabolic acidosis could be confirmed, either by means of arterial blood gas analysis, or measurement of bicarbonate on venous plasma or serum. -hydroxybutyrate is the predominant ketone in DKA and is the major contributor to the acidosis. However, the urine ketone stick test (Ketostix , Bayer Diabetes, Berkshire, UK) uses a nitroprusside reaction and gives a semi-quantitative measure of acetoacetate, but not -hydroxybutyrate. This is important because -hydroxybutyrate is the predominant ketone in DKA and the major contributor to the acidosis. In addition, -hydroxybutyrate is oxidized to acetoacetate as the ketosis resolves. Thus, if urinary urine ketone stick tests alone are used to guide treatment, a false impression may be gained that the ketoacidosis is not resolving. A further limitation of urine ketone measurement is that it measures the average concentration in the urine held in the bladder since the last void. Patients with DKA are usually dehydrated on admission, and may not urinate spontaneously for several hours (some may require catheterization). This may lead to further difficulties evaluating the current biochemical state of the patient. In 2010, the Joint British Diabetes Society Inpatient Care Group (JBDS) published a guideline on the management of DKA in adults; this was subsequently updated in 2013. The diagnostic criteria for DKA used by JBDS are shown in Table 1. They recognize that the predominant problem is not hyperglycaemia, but acidosis – or more accurately, ketosis. The potential problems with urine ketone measurement outlined above led the authors of the guideline to advocate instead the use of point-of-care blood ketone meters in the management of DKA. A meta-analysis comparing the use of blood ketone measurement with urinary ketone measurement in DKA showed that, in the few studies that were good enough to include, measurement of blood ketones was associated with reduced emergency department assessment, hospitalizations and a shorter time to recovery. In addition, previous data appeared to show comparable accuracy between capillary and venous blood samples. In the UK, two point-of-care testing (POCT) meters are widely used to measure blood ketone concentrations: the GlucoMen LX Plus (A Menarini Diagnostics, Wokingham, Berkshire, UK) and the Freestyle Optium Neo (Abbott Diabetes Care, Maidenhead, Berkshire, UK). The GlucoMen LX Plus clearly states in its product insert that the GlucoMen LX s-Ketone sensors ‘should not be used to diagnose diabetes, DKA or to test new-born babies’. However, elsewhere, under prevention and