Abstract
Sir Steve Redgrave: ‘Diabetes has to live with me, not me live with it’ (BBC Online News 15 June 2009)
When someone is told they have diabetes mellitus their world changes for ever. A hundred and one questions arise. Fear, mainly of complications, quickly changes to questions of managing food and lifestyle. A series of consultations with different health-care professionals helps the patient through what is often a period of difficult uncertainty. Self-monitoring of blood glucose (SMBG) concentration forms an important part of the package of measures that helps patients to understand their diabetes and also come to terms with the diagnosis of diabetes. For the healthcare professional looking after the patient, SMBG is an important tool to determine the interplay between diabetes and the patient's lifestyle and helps to tailor clinical and lifestyle advice. 1
The type of diabetes and the manner in which the diagnosis of diabetes is made generally determines how SMBG is used. In the precipitous and stormy presentation of type 1 diabetes and subsequent course of the disease there is little choice for health-care professionals and patients but to closely monitor blood glucose. When, for example, type 2 diabetes is diagnosed in a non-urgent setting such as after a routine oral glucose tolerance test or incidentally on a screening medical there is still debate on the benefits of initiating or continuing SMBG. 2–4
In this issue of the journal, O'Kane and Pickup 5 explore the benefits of SMBG. They point out that SMBG is an example of a monitoring test that was adopted before robust evidence for clinical efficacy was available. Much of the controversy arises because of the relative invasive nature of SMBG, issues of patient compliance and lack of understanding of meaning of SMBG values and health-care professionals' lack of appreciation of the limitations of SMBG.
It is recognised that those patients who attend clinics on a regular basis fare better and have fewer complications. What is also clear is that encouraging self-care in people with diabetes mellitus results in lower complication rates. 6 Whether SMBG helps in any way or how it helps is unclear. To answer this question in a trial would involve examining the effects of regular long-term SMBG on outcomes determining morbidity and mortality. Given the intraindividual and between patient variation in glycaemic control over a period of time, the progressive nature of diabetes mellitus that results in incremental dose adjustment of hypoglycaemic agents and polypharmacy, it would be difficult to obtain precise answers on SMBG. Moreover, many pragmatic studies are affected by the fact that patients do not always carry out SMBG on a regular basis and many do not acquire the interpretative skills for effecting behaviour change. 7
Another variable is the lack of consensus on the frequency of SMBG. Given the invasive nature of SMBG an intensive seven-point check used in the months after the diagnosis of diabetes often gets reduced to a two-point check or sporadic testing. It is not uncommon for patients to just check their fasting or bedtime blood glucose values with very few tests done during the working day. So a health-care professional initiated test becomes a test that the patient uses in the long term. Who decides how frequently SMBG is carried out is important in determining the efficacy and utility of SMBG. 8
The principles that apply to ordering laboratory tests generally also apply to SMBG. The key lies in the understanding and interpretation of the data obtained from the test. For SMBG this could be deriving the average value from a multipoint check for the physician to assess glycaemic control or the measures a patient takes in response to a high morning value or a high postprandial value or low bedtime blood glucose value. Yet, excessive or obsessive testing or testing blood glucose without taking action becomes an exercise in futility and is wasteful of resources in both privatised and nationalised systems of health care.
The essence of SMBG is its flexibility of use. It is, therefore, no surprise that different studies and meta-analyses have yielded conflicting results. For a test that is carried out by a patient, usually episodically, using a rigid evidence-based approach to examine the utility of SMBG may not be the best way to evaluate its benefits. On the other hand, health-care organisations do need data to determine the utility of tests. 9 The best way to tackle inappropriate use of SMBG is to educate both health-care professionals and patients.
As an example, simply prescribing lifelong treatment such as antihypertensive agents or statins does not ensure that the patient will take their medication regularly. In order that the patient understands the benefits of taking the drugs, clinic attendances and regular support and reassurance help compliance and understanding. A similar approach is necessary with SMBG where health-care professionals not only review or adjust medication for diabetes, but review the need or the frequency of SMBG. While the patient has ownership of SMBG, it is the role of the health-care professional to educate and moderate the judicious use of SMBG. They also need to reassess that the patient is still able to effect lifestyle changes or adjust hypoglycaemic agents in response to SMBG values. The ideal end state would be where a patient with diabetes mellitus is able to have as ‘normal’ a life as someone without diabetes with SMBG in the background used as and when necessary to either adjust food intake, exercise or the dose of insulin. There will always be a need for SMBG as an adjunct to glycated haemoglobin (HbA1c) to provide short-term measures of control and for patient feedback and education. 10 Notwithstanding the debate on who needs SMBG and how frequently it should be carried out, the answer for appropriate SMBG use lies in educating both patients and health-care professionals, and as with most issues in medicine, communication with the patient is the key. 11