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Assessing blood glucose control in diabetes

Elaine Campbell
RGN BSc(Hons) NP DipN NDNCert
Practice Nurse
Basingstoke, Hants

Diabetes is a condition that impacts on the individual from the moment of diagnosis, for the rest of their life. Keeping control of their blood sugar levels becomes the overriding goal of the health professionals, whose concern is to prevent the morbidity and mortality associated with the condition.

Whilst assessment of blood sugar control is only one aspect of the management of diabetes, it is the key to prevention of the other disease processes associated with it.(1,2)

As well as blood sugar control being essential for the individual's personal long-term health,there is also the wider public health concern with reducing the enormous cost to health and social services of dealing with the consequences of poorly controlled diabetes.

Practice nurses are ideally placed to advise and support their patients as they make adjustments to their lifestyles to benefit their health. Ensuring effective monitoring takes place, either within the practice or by some form of self-monitoring is an integral part of this role.

The role of the nurse is:

  • To guide and support the individual in making decisions about the most appropriate method of testing for them.
  • Provide information on the differing methods.
  • Teach and support them as they learn to begin self-monitoring.
  • Show them how to interpret the results so that the information can be acted on.

Practice or clinic appointments
Diabetes control can be assessed within the practice at routine appointments by finger prick blood glucose readings, urinalysis and laboratory blood tests.

Increasingly the blood test of choice is estimation of HbA1c. This assesses the level of overall control achieved in the previous eight to 12 weeks. The "normal" range varies between laboratories, but in general a reading below 7% is acceptable.(2,3) Doctors may feel that treatment changes should be instigated only after confirmation of a raised HbA1c as this can be seen as a more reliable assessment of control than self-monitoring. However, if this is the sole method of assessment, the individual can lose the benefits of the active involvement in self-monitoring.

Self-monitoring
For those willing and able, some form of self-monitoring is desirable. Self-monitoring can be an educational tool, helping individuals to understand how their diet and lifestyle, along with their medication, affects their body's ability to function efficiently.(4,5) It provides an objective assessment of control independent of how they feel. It can provide reassurance (if their control is good), facilitate decision-making regarding treatment and lifestyle adjustments, and is consistent with the ethos of empowering people to become "expert patients".(6)

However, it is not always liberating for the individual to have the chore of testing or the responsibility for decision-making that comes with it. Some may have their view of themselves as "failures" reinforced if they do not manage to reduce their blood sugars.(7) If self-monitoring is imposed on those unable to cope with it, either physically or psychologically, then that individual's self-esteem and their ability to cope with their condition could be damaged.(8)

Frequency of testing
Local diabetes centres may have differing policies on the advice they give with regard to frequency of testing. In general, testing will need to be done more often when newly diagnosed, when there is deteriorating control, when commencing insulin therapy, with change of medication or lifestyle, or during illness or stress.

It is advisable to test at varying times of day in order to assess any patterns in high or low readings. Change of treatment should be made rarely on "one-off" readings, but when there is evidence that at a particular time of day the reading is always high or low.

Readings that are near normal values before a meal demonstrate that the medication and food taken at the previous meal is adequate. Any increase in that medication, reduction of food intake or increase in physical activity would then risk hypoglycaemia.

There is increasing evidence that in type 2 diabetes postprandial peaks in blood glucose levels significantly increase the risk of developing diabetic complications,(9) although how this will affect the management of the condition is still unclear. It is possible that in future we will be concentrating on this measurement to a greater degree than at present.

If testing is too infrequent there is the risk that the individual will "forget" about their diabetes and there may be nothing to alert them to deteriorating control. This may be of more concern to the health professional than to themselves, yet would substantially increase their risk of future poor health.

The frequency of testing must be appropriate for the needs of both the patient and the professionals. There is little point gathering information that will not alter management decisions.

Cost of monitoring
The cost to the NHS of monitoring diabetes control is largely borne by the hospital laboratory services and the general practice drug budget, but in theory should be saved in the long term by the reductions in the cost of treating complications. The cost to the patient may be prescription charges (for those not on diabetes medication), or the purchasing of electronic meters.
Pharmaceutical companies are increasingly supplying meters free of charge to clinics and practices, with the effect of making it much easier to start patients on blood glucose self-monitoring. They invariably recoup their investment due to the cost of the test strips.

The effect on a practice's drug budget of transferring all patients from urine testing (£2-£3 for 50 strips) to blood glucose monitoring (£13-£15 per 50 strips) would be enormous and often inappropriate.

New-technology devices are also costly. The Glucowatch Biographer is a glucose-monitoring device that uses an extremely low electric current to pull glucose through the skin.
It has a very limited role in glucose monitoring at present and is expensive, with the monitoring strips costing £50 for 16.

Conclusion
All those with diabetes need to have some form of monitoring of their blood glucose control, including at minimum an annual laboratory blood test for HbA1c (or equivalent).

The method of self-monitoring will very much depend on the wishes and capabilities of the individual person, but they need guidance from their health professionals as to the appropriateness of their decision and the frequency of testing.

There is little point performing tests unless the information gained will be acted upon.

The goal of diabetes care is the prevention of long-term health problems by use of optimum therapy without causing side-effects (eg, hypos). The development of reliable, affordable electronic blood glucose meters has dramatically improved the ability to achieve this, but comes at cost to the practice and needs to be used appropriately.

Practices should have a policy on the advice they wish to be given to patients concerning the type and frequency of monitoring written into their clinic guidelines.

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References

  1. UKPDS Group. Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33). Lancet 1998;352:837-53.
  2. Rodgers J. Pharmacological interventions in type 2 diabetes. Br J Nurs 2000;9(13):866-70.
  3. Williams G, Pickup C. Assessing control in diabetes. Handbook of Diabetes. Oxford: Blackwell Science; 2000.
  4. Craddock S. Blood glucose monitoring by people with diabetes. Prof Nurse 1997;13(3):S11-S13.
  5. Burden M. Diabetes: blood glucose monitoring. Nurs Times 2001;97(8):36-9.
  6. Department of Health. The Expert Patient: A new approach to chronic disease management for the 21st century. London: Department of Health; 2001.
  7. Snoek F. Psychology and hypoglycaemia. Conference report of the 5th meeting of ABCD. Practical Diabetes Int 2000;17(2):65-6.
  8. Rodgers J. Patient education for people with type 2 diabetes. Primary Health Care 1999/2000; 9(10):17-21.
  9. Tuomilehto J. Glucose peaks - the hidden danger in type 2 diabetes. Practical Diabetes Int 2001;18(1):S7-S9.

Resources
Diabetes UK
W:www.diabetes.org.uk
Diabetes NSF updates
W:www.doh.gov.uk/nsf/diabetes/index.htm
Site relating to: Testing times: a review of diabetes services in England and Wales. April 2000
W:www.diabetes.audit-commission.gov.uk
Up-to-date list of publications from the Dept of Health
W:www.doh.gov.uk/whatsnew/index.htm.