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Self monitoring of blood glucose levels

Key learning points:

- Self monitoring of blood glucose (SMBG) is clearly important in type 1 diabetes and insulin requiring type 2 diabetes

- SMBG in type 2 diabetes for those not using insulin is an effective intervention if the procedure is integrated into a structured education package

- SMBG procedure requires some key elements for accuracy of blood glucose results

Research has shown there is a clear link between high blood glucose levels and the microvascular and macrovascular complications of diabetes in both type 1 diabetes (1) and type 2 diabetes. (2) As a result of this research, people with diabetes and their healthcare professionals think about self-management and professional healthcare management with a view to avoiding these complications through the achievement of normal or near-normal blood glucose levels.

Self-monitoring of blood glucose (SMBG) is indisputable for people with type 1 diabetes. It enables the individual to observe patterns of blood glucose results and adjust insulin doses accordingly. SMBG supports the management of hypoglycaemia, hyperglycaemia, illness, and activity/exercise. More recently through structured diabetes education, people with type 1 diabetes have been taught to match their insulin doses to carbohydrate intake precisely (for example they may take 1 unit of fast acting insulin for every 10 grams of carbohydrate). (3) Structured diabetes education also teaches individuals to perform 'correction' doses, for example, they may want to reduce a pre-meal blood glucose and so may take an extra 1 unit to reduce the pre-meal result by 2-3 mmoles/l in addition to their normal pre-meal insulin dose. This can only be done effectively by using blood glucose monitoring. Similarly for those with type 2 diabetes requiring insulin treatment, blood glucose monitoring is considered an essential part of the package of self-management for many of the reasons above, although, insulin adjustment tends to be done differently depending on the insulin regimen.

Where SMBG becomes controversial is with patients who have type 2 diabetes and who are not on insulin therapy. There has been a great deal of research over the last 10-15 years questioning
the usefulness, and the cost effectiveness of SMBG for people with type 2 diabetes on diet and lifestyle advice and/or oral hypoglycaemic agents.

The first part of this paper will discuss some of the key studies entering into this argument about SMBG in type 2 diabetes. The second part of the paper will describe the critical factors in making sure that training of patients performing blood glucose monitoring is carried out accurately.

The cost of blood glucose monitoring

Blood glucose monitoring is expensive. A recent report on prescribing for diabetes in England from 2005-2006 until 2013-14 shows a “21.4% increase in the total cost of blood glucose-monitoring supplies. The number of items prescribed has increased by 14.4%. (4)

The annual cost of blood glucose testing supplies for the NHS (in England) stands at £172 million, representing 1% of the total spend on diabetes and its complications.” (4)

Critics of blood glucose monitoring in type 2 diabetes state that it is not cost-effective, (5) that any positive effect wains after 12 months (6) and can be associated with higher scores on a depression subscale. (7) On the other hand supporters state that blood glucose monitoring if properly supported by education in relation to how results are interpreted and actioned can have a significant effect on improving glycaemic control. (8,9,10) 

The evidence

A systematic review was commissioned by the National Institute for Health Research (NIHR) programme. (11)

It reported that:

- People felt motivated by SMBG and were able to use it to relate to self-management and lifestyle strategies of their diabetes.

- There was evidence that people with type 2 diabetes on lifestyle and /or medication, who learned about SMBG through a structured education programme showed significant reduction in long-term blood glucose levels as demonstrated by HbA1c.

 A recent meta-analysis of individual patient data found that SMBG in people with non insulin taking type 2 diabetes was not useful. (5)

- Results were not convincing for clinically meaningful effect of clinical management in those who performed SMBG despite the HbA1c (long-term blood glucose control was statistically significant in the SMBG patients.

- They conceded that further evaluation of SMBG in type 2 diabetes needed to be closely linked to behavioural strategies - these results were largely supported by a more recent systematic review. (6) 

This ongoing controversy led the prestigious journal Diabetes Care to issue an invitation to two authors with opposing views on the usefulness of SMBG in non-insulin taking type 2 patients to publish their arguments for and against. (12,13) Malanda the author of the most recent systematic review argued that there was no substantial evidence demonstrating that SMBG had a positive effect on reducing blood glucose levels in people with type 2 diabetes. Polonsky and Fisher provided an alternative explanation stating that implementing SMBG in unstructured ways was indeed a waste of resources but as part of structured educational package their evidence has demonstrated that those with suboptimal blood glucose control SMBG can be used in partnership with health care professionals to significantly improve blood glucose control.

So this suggests that not only is SMBG useful for all those with type 1 diabetes and insulin requiring type 2 diabetes patients but also for individuals with type 2 diabetes who would like to use it as a way of monitoring their condition. Indeed Polonsky et al found that offering structured training not only to patients performing SMBG but also to their clinicians to help them understand how to support patients, may have enabled the very significant improvements reported. (8) The importance of providing meaningful education to people with type 2 diabetes not on insulin but who want to use SMBG is acknowledged in the NICE Guidance on type 2 diabetes. (14)

Advancing blood glucose meter technology

Blood glucose meters have become easier to use over the last few years, and companies have developed technology to make the procedure of SMBG more user friendly for individuals and this contributing to a more accurate result. Most of the development has been in relation to:

- Rapid test time - a blood glucose meter reading can now be done within seconds.

- Small blood sample size.

- Calibration - some meters now do not need calibrated with the batch of strips being used.

- Strip handling - some meters have strips inbuilt within the meter.

All of these developments make the procedure simpler with less room for error. If an error occurs meters tend to give an error message to alert the individual that the test needs to be repeated. Other data can be entered such as insulin dosage, meal and activity times and targets blood glucose levels. It is now possible for meters to recommend insulin doses if results are out of the target range. Comprehensive descriptions of most meters can be found on

What do patients need to know?


There are a few key elements of SMBG that should form part of the educational package when providing training in SMBG:

Hand washing

Hand washing is vital to avoid contaminates on the skin which may give an inaccurate result. For example, handling a sugary food prior to testing may give a false high reading. Hands also need to be dried properly as residual water might give a false low blood glucose reading.

Blood sample size

A small sample size may give a false low reading. Fortunately most meters in common use will give an error message if the sample size is too small.


Many meters require the user to match the code on the strip container to the meter. If this is not done then blood glucose results can be significantly inaccurate.

Frequency of SMBG

Polonsky et al reported that the patients who had received structured SMBG educational intervention had a significant reduction in long-term blood glucose control compared with the control group even although were actually performing SMBG less. (7) They suggest that quality of SMBG that includes meaningful tests with positive action rather than quantity of testing is more useful. In this study both patients and clinicians were taught how to utilise protocols to support action on blood glucose results. Patients sampled when they thought necessary however prior to clinic visits would provide three days of seven point blood glucose profile, including fasting and between meal tests for mutual discussion. This may not be practical or necessary outside of research conditions but fasting and post prandial testing will give different information and may lead to different kinds of actions.

Quality control

A quality control solution is provided by some companies so that accuracy of results can be checked against a controlled glucose solution. This will reassure that both the meter is working properly and that the procedure is correct.  

Strip and device storage

Incorrect storage of strips and meters might result in deterioration of their effectiveness. Patients have been known to take strips out of the storage bottle and keep them loose or in another container. This means they may be contaminated or be exposed to, for example humidity, temperature extremes or may exceed their expiry date. Expiry date may vary between strip types and may depend on when the strip container has been opened. Meters can also be sensitive to temperature and altitude.


Driving regulations changed in 2011 and now require that drivers of group 1 vehicles with type 1 diabetes and those with type 2 diabetes on insulin test their blood glucose regularly at least twice daily, and at times relevant to driving including two hourly during a long drive to avoid hypoglycaemia. (15)

Group 1 drivers oral medication, including sulphonylureas and post prandial regulators, which carries a risk of hypoglycaemia, may also be required to monitor especially at times relevant to driving. (15)

Group 2 drivers on oral medication including sulphonylureas and post prandial regulators, which carries a risk of hypoglycaemia, must monitor regularly and especially at times relevant to driving. (15)


Many nurses will be bound by local guidance restricting blood glucose monitoring for patients with type 2 diabetes not on insulin therapy. However there is now a growing body of robust evidence that suggests if included as a component of self-management education in people with type 2 diabetes then it can be cost effective and improve quality of life. Diabetes UK is very clear in its position statements on this topic that there should be no postcode lottery and that every individual should be assessed and supported to perform SMBG if appropriate. (15,16,17) The actual procedure has become easier over the last few years. Utilising SMBG into existing self-management strategies is the challenge for both nurses and patients working together to improve diabetes self-management.


1. Diabetes Control and Complications Trial Research Group: The effect of intensive treatment of diabetes on the development and progression of long term complications in insulin dependent diabetes. The New England Journal of Medicine. 1993:329:977-986

2. United Kingdom Prospective Diabetes Study Group.UK Prospective Diabetes Study 23: risk factors for coronary artery disease inn on-insulin dependent diabetes. The British Medical Journal 1998; 316:823-828

3. DAFNE Study Group. Training in flexible, intensive insulin management to enable dietary freedom in people with type 1 diabetes: dose adjustment for normal eating (DAFNE) randomised controlled trial. The British Medical Journal 2002; 325(7367):746

4. Health & Social Care Information Centre. Prescribing for Diabetes. England 2005-06 to 2013-14. 12. 2014. (accessed 23rd April 2015)

5. Farmer AJ, Perera R, Ward A, Heneghan C, Oke J, Barnett AH et al. Meta-analysis of individual patient data in randomised trials of self-monitoring of blood glucose in people with non-insulin treated type 2 diabetes. The British Medical Journal 2012; 344: e486-e486.

6. Malanda UL, Welschen LM, Riphagen II, Dekker JM, Nikpels G, Bot SD. Self-monitoring of blood glucose in patients with type 2 diabetes mellitus who are not using insulin. Cochrane Database Syst Rev 2012;1:CD005060

7. O'Kane MJ, Bunting B, Copeland M, Coates VE; ESMON study group. Efficacy of self-monitoring of blood glucose in patients with newly diagnosed type 2 diabetes (ESMON study): randomized controlled trial. The British Medical Journal 2008'336:1174-1177

8. Polonsky WH, Fisher L, Schikman CH, Hinnen DA, Parkin CG, Jelsovsky Z, et al. Structured Self-Monitering of Blood Glucose Signigicantly Reduces A1C Levels in Poorly Controlled, Noninsulin- Treated Type 2 Diabetes. Results from the Structured Testing Program study. Diabetes Care 2011;34:262-267.

9. Bosi E, Scavini M, Ceriello A, Cucinotta D, Tiengo A, Marino R, et al. Intensive Structured Self-Monitoring of Blood Glucose and Glycemic Control in Noninsulin-Treated Type 2 Diabetes. The PRISMA randomized trial. Diabetes Care 36:2887-2894,2013

10. Tanenbaum ML, Leventhal H, Breland JY, Yu J, Walker EA, Gonzalez JS. Successful self-management among non-insulin-treated adults with Type 2 diabetes: a self-regulation perspective. Diabetic Medicine Doi:10.1111/dme.12745

11. Clar C. Bernard K, Cummins E, Royle P, Waugh N; Aberdeen Health Technology Assessment Group. Self-monitoring of blood glucose in Type 2 diabetes: systematic review. Health Technology Assessment 2010;14:1-140

12. Malanda UL, Bot SD, Nijpels G. Self-Monitoring of Blood Glucose in Noninsulin-Using Type 2 Diabetic Patients It is time to face the evidence. Diabetes Care 2013;36: 176-178

13. Polonsky WH, Fisher L. Self-Monitoring of Blood Glucose in Noninsulin-Using Type 2 Diabetic Patients right Answer, but wrong question: self-monitoring of blood glucose can be clinically valuable for noninsulin users. Diabetes Care 2013;36 179-182.

14. NICE. Type 2 diabetes: The management of Type 2 diabetes. 1.4 Self Monitoring of plasma glucose. (accessed 23rd April 2015)

15. Diabetes UK. Self-monitoring of blood glucose (SMBG) for adults with Type 2 diabetes. April 2013 (accessed 23rd April 2015)

16. Diabetes UK. Self-monitoring of blood glucose (SMBG) for adults with Type 1 Diabetes. August 2012. (accessed 23 April 2015)

17. Diabetes UK. Access to test strips. A postcode lottery. Self-monitoring of blood glucose by people with Type 1 and Type 2 diabetes. August 2013. (accessed 23 April 2015)