Continuous blood glucose monitoring: detection and prevention of hypoglycaemia

Abstract

For patients with diabetes the best defence against the consequences of either hypoglycaemia or hyperglycaemia is to be able to recognise it and treat it promptly. In normal activity patients have problems in their diabetes management despite adequate knowledge and therapies. Glucose sensors have been developed that can be inserted subcutaneously in order to continuously monitor glucose concentrations over several days. Studies have been conducted with continuous glucose monitoring of patients with diabetes that reveal previously unrecognised periods of hypoglycaemia, ranging from a few minutes to several hours. Continuous monitoring during the nocturnal period can reveal hypoglycaemic and hyperglycaemic episodes and the insulin usage can subsequently be adjusted to decrease the incidence, which may lead to reduction in the risk of long-term complications. Preliminary studies have already shown that better management can be obtained, with reductions in HbA1c levels, when 24-h profiles of glucose concentrations are obtained. Our ongoing study of patients with type 1 diabetes assessing continuous glucose monitoring have shown that glucose concentrations are only within a target range of 4-10 mmol/l for about 35 per cent of the time. Such measurements are leading to better individualisation of diabetes management. While the present generation of glucose monitors only provide retrospective profiles, newer sensors are being developed that can detect real-time changes. These may form the basis of an alert to hypoglycaemic levels or ultimately be connected directly to continuous insulin infusion, particularly with rapid-acting insulin analogues, to maintain glucose within normal physiological limits.