Self-Monitoring Blood Glucose (SMBG) in Diabetes Mellitus

Blood glucose measurements provide people with diabetes mellitus with an accurate method of measuring blood glucose concentrations and therefore detecting both hyperglycaemia or hypoglycaemia. There is currently a great deal of debate about the need and frequency of blood glucose monitoring in diabetes mellitus. The debate is focused on the balance between the high and rising NHS expenditure on blood glucose monitoring and the importance of the involvement and empowerment of people with diabetes in their own care.¹
Although glucose meters are not prescribable at NHS expense, they are often provided free to patients from the manufacturers on the basis of income made from the testing strips, which are prescribable at NHS expense and each type of testing strip is specific to each monitor.

• Patients should be given adequate training in self-monitoring techniques, including interpretation of results and appropriate action when required.
• Patients and health care professionals should be clear what they hope to achieve by self-monitoring blood glucose. Self-monitoring must be part of a broad education and empowerment process for the person with diabetes and not as a stand-alone process.² Many people with diabetes provide books full of results but still don't fully understand the implications of the results or have a full understanding of diabetes mellitus and its implications and management.
• Glucose testing meters should be checked and re-calibrated at recommended intervals to ensure accuracy.

• Strict control of blood glucose levels improves the outcomes in patients with either type I or type 2 diabetes.
• However, it is not clear whether self-monitoring contributes to this improvement.³
• For self-monitoring of blood glucose to be most useful, it should form part of a wider programme of management.
• Self-monitoring is most appropriate for patients with type I diabetes or type 2 diabetes who use insulin regimes and adjust their dose as a result of blood glucose testing, and for all diabetic patients when they have intercurrent illness.
• There are no specific national guidelines available and the need and extent of home glucose testing will depend on the treatment required for diabetes, the degree of glycaemic control and the preferences and needs of each individual.⁴

Patients using insulin⁵

• Patients who are using insulin but have good glycaemic control still need to perform blood tests regularly.
• The regime should be appropriate and acceptable to each individual patient.
• Those using twice daily insulin therapy should be educated to undertake SMBG at least twice daily, varying the time between fasting, premeal and postmeal, to help build up a profile of glycaemic control throughout the day. Some patients prefer to perform frequent tests on 2 or 3 days in the week and then again only if concerned about possible hypoglycaemia.
• Frequent self monitoring is required during illness (least four times a day).
• Ideally patients who alter insulin doses at mealtimes should be encouraged to monitor at least four times daily.
• Patients with symptoms of nocturnal hypoglycaemia or resistant morning hyperglycaemia should measure blood glucose levels in the early hours of the morning (between 2 am and 3 am).
• Patients who are pregnant or hoping to become pregnant, or using insulin pump therapy should monitor their blood glucose levels between 4-6 times daily.
• Patients with type 2 diabetes on insulin with oral hypoglycaemic agents should be encouraged to self monitor at least once daily, varying the time between fasting, premeal and postmeal, to identify trends.

People with type 2 diabetes who are not using insulin

• There is no evidence that blood testing is more effective than urine testing at improving blood glucose control in people with type 2 diabetes.³
• Many people with type 2 diabetes, especially those who are either diet controlled or taking only metformin and/or a glitazone drug do not need to perform home blood glucose monitoring. There is no risk of hypoglycaemia and glycaemic control is better and adequately monitored by regular testing of glycosylated haemoglobin.
• Patients with type 2 diabetes who are taking a sulphonylurea are at risk of hypoglycaemia and so have a greater need to self-monitor blood glucose.
• It is not known what the ideal frequency of self-monitoring should be in type 2 diabetes. Current recommendations are based on consensus opinion.