Healthy Skepticism Library item: 11383
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Publication type: news
Gadsby R.
Are blood glucose strips worth £100 million?
Pulse 2007 Aug 23
http://www.pulsetoday.co.uk/story.asp?sectioncode=18&storycode=4114175&c=1
Full text:
Dr Roger Gadsby reviews the research that casts doubt on whether the NHS gets good value for the money it spends on self-monitoring of blood glucose
What is the controversy about?
Self-monitoring of blood glucose (SMBG) costs the NHS more than £100m per year. In many PCTs the cost of SMBG strips exceeds the cost of insulin. Is this money well spent?
People who use insulin to treat their diabetes have an absolute requirement to be able to monitor their blood glucose to up-titrate their dose, and then adjust their insulin dose and to monitor for hypoglycaemia.
However, there is uncertainty about whether people with type 2 diabetes controlled on oral agents and/or diet have improved control of glycaemia (as measured by HbA1c) by doing SMBG or if simply having a regular HbA1c measurement is enough.
The uncertainty exists because the evidence is inconclusive. Some, but not all, observational studies have shown that even in patients treated by diet alone, those who measure their blood glucose more often have better outcomes. This may just indicate that those who are highly motivated as reflected in a frequency of SMBG are likely to do well in the long-term1.
Some studies have randomised patients to SMBG or no monitoring. A meta-analysis of these studies reported a small improvement in HbA1c of 0.3% in those doing SMBG but the confidence intervals were so wide that the difference was not statistically significant2.
It is quite difficult to see how a glycaemic- monitoring programme without an education component could alter glycaemic control. People with diabetes need to be able to understand, interpret and act upon the results from SMBG otherwise they are of no benefit.
As healthcare professionals we have all been given SMBG diaries by patients where all the measurements are ‘normal’ and were written in the same coloured pen, probably the night before the visit to the diabetic clinic. Patients want to please their healthcare professionals and so often fill in the diaries regularly to please us rather than use the results for their own benefit. The role of education therefore needs to be evaluated in SMBG research.
What is the current situation?
There is uncertainty about the value of routine SMBG in people with diabetes controlled on oral agents and/or diet.
What is the result of this controversy?
Some PCTs developed policies to try to restrict SMBG, which created a lot of concern from patient groups such as Diabetes UK. There was a widespread view that more research was needed and the NHS and health technology assessment programme funded a study which has just reported.
The latest evidence
The Diabetes Glycaemic Education and Monitoring Study (DiGEM) recruited 453 people with type 2 diabetes treated with oral agents from general practices in Oxfordshire and South Yorkshire. Their mean age was 65.7 years, and mean HbA1c was 7.5%. They were randomised into three groups:
• the control group (n=153) had standardised care, no SMBG, and HBA1c measurements every three months.
• the second group (n=150) had the above plus SMBG with advice to contact their doctors for interpretation of the results
• the third group (n=151) had standardised care plus SMBG with additional training of patients in interpretation and application of the results to enhance motivation and maintain adherence to a healthy lifestyle. The groups were well-matched for all baseline parameters such as duration of diabetes, HbA1c level and current treatment.
The main outcome measure was HbA1c at 12 months.
The results showed no statistical difference in HbA1c between the three groups. The authors conclude that evidence is not convincing of an effect of SMBG. The doubt exists on self-care, whether or not the patients have instruction in improving glycaemic control, compared with usual care in reasonably well controlled non-insulin treated people with type 2 diabetes3.
What effects have the various studies had on patients?
The advice about SMBG given to people with type 2 diabetes not on insulin has varied across the UK. Some believe that the information provided by SMBG is a powerful motivating factor in encouraging self-care by allowing people to see the impact of eating and exercise on glucose levels.
SMBG is usually a significant component of the self-management education for people with diabetes which all newly-diagnosed people with type 2 diabetes are encouraged to attend.
The results of the DiGEM study do not provide us with guidance on whether SMBG is a valuable part of education at diagnosis of type 2 diabetes, and until there is stable glycaemic control.
What should GPs be doing now?
The results of this study should encourage GPs to discuss the value of continuing with regular SMBG with all people with type 2 diabetes not using insulin. It gives us the confidence to encourage discontinuation of SMBG if the person is well controlled (as evidenced by HbA1c measurements at or near target), in whom the SMBG results are of no benefit.
The question of the role of SMBG in the education and empowerment of people newly diagnosed with type 2 diabetes awaits further research.
Dr Roger Gadsby is a GP in Nuneaton, associate clinical professor at Warwick medical school University of Warwick and medical adviser, Warwick Diabetes Care
Competing interests None declared
References :
1 Heller S. Self monitoring of blood glucose in type 2 diabetes (editorial). BMJ 2007;335:105-6
2 Coster S, Guillford MC, Seed PT et al. Self monitoring in type 2 diabetes:a meta-analysis Diabetic Medicine 2000;17:755-61
3 Farmer A, Wade A, et al on the behalf of the DiGEM trial group. Impact of self monitoring of blood glucose in the management of patients with non-insulin treated diabetes: open parallel group randomised trial. BMJ 2007; 335:132-6
