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Self-monitoring of blood glucose in patients with type 2 diabetes not on insulin

Self-monitoring of blood glucose (SMBG) in patients with type 2 diabetes not on insulin has little evidence of benefit. In the majority of recent trials SMBG has been found to be provide no improvements in outcomes and may be associated with a reduction in quality of life.1,2

SMBG does not enhance patient education

SMBG is sometimes performed for people with newly diagnosed type 2 diabetes, as part of a self-management education programme, however, a recent review3 and randomised controlled trial4 have failed to demonstrate that the addition of SMBG to an education programme improves glycaemic control compared to education alone.

SMBG results in significant cost

In New Zealand, approximately $9.1 million is spent annually on test strips for patients not on insulin. By contrast, approximately $3.15 million is spent on medications for these people.5

Limited role of SMBG

For patients not on insulin, SMBG does have a role in a limited number of situations, including:2,6

  • Patients on sulphonylureas where there is a potential risk of hypoglycaemia, e.g. illness, dose increments
  • To optimise glycaemic control prior to conception and during pregnancy
  • Prior to initiation of insulin

For SMBG to be clinically effective in these situations the doctor and patient need to agree on a clear purpose or goal to testing, and that the benefits of continued SMBG be reassessed on a regular basis.

The report below provides an opportunity for you to reflect on your patterns of prescribing of test strips, for people with type 2 diabetes who are not on insulin. We have provided data for your patients controlled by diet alone, on metformin alone, and those on sulphonylureas.

Notes:

Time period: 1 August 2009 to 31 July 2010

Data is assigned to you based on the recorded NZMC number for prescriptions written for diabetic medications and/or diabetic testing strips. Data has been excluded where the NZMC number or the encrypted NHI was not recorded.

Females between the age of 12 and 45 prescribed metformin only have been excluded from the analysis due to the possibility of being on metformin for PCOS.

Personalised feedback

Diet-controlled type 2 diabetes

For people with diet-controlled type 2 diabetes, SMBG is not recommend as part of routine care and glucose levels are best monitored by HbA1c testing.6 Frequent use of SMBG for these people is not associated with better glycaemic control and there may be psychological disadvantages.

You have X patients who were dispensed test strips but no diabetic medication.

On average these patients receive X test strips each per year.

On average, each New Zealand GP has 5 patients who were dispensed test strips but no diabetic medication.

These patients are receiving approximately 162 test strips each per year.

Metformin alone

Metformin lowers blood glucose in patients with type 2 diabetes primarily by decreasing hepatic glucose output and it is also thought to increase glucose uptake by skeletal muscle. Because insulin secretion is unaltered, hypoglycaemia is not a side effect of metformin. People whose diabetes is managed using metformin alone do not need routine SMBG, although people using both insulin and metformin would require SMBG as part of their insulin regimen.

You have X patients on metformin* who were dispensed test strips.

On average these patients receive X test strips each per year.

On average, each New Zealand GP has 6 patients who are on metformin only and also performing SMBG.

These patients are receiving approximately 227 test strips each per year.

Sulphonylureas

All sulphonylureas have the potential to cause hypoglycaemia. In the past longer acting sulphonylureas (e.g. glibenclamide, chlorpropamide) were more widely used. Now shorter acting sulphonylureas (e.g. glipizide, gliclazide) are preferred and the risk of hypoglycaemia is much reduced.

The potential of shorter acting sulphonylureas to cause hypoglycaemia remains, however this is uncommon and usually indicates a need for dose reduction or the presence of renal or hepatic dysfunction. Caution is needed when these medications are used in elderly people and in those with renal or hepatic impairment.7

Patients who take a sulphonylurea, either alone or in combination with other oral therapy, may elect to test their blood glucose periodically because of this small increased risk of hypoglycaemia,2 however, there is no clear evidence that SMBG testing (regardless of the type of oral therapy used) is associated with clinically significant improvements in glycaemic control.2,8

You have X patients on sulphonylureas who were dispensed test strips.

On average these patients receive X test strips each per year.

On average, each New Zealand GP has 9 patients who are on sulphonylureas and also performing SMBG.

These patients are receiving approximately 409 test strips each per year.

References:

  1. Clinical Knowledge Summaries. Diabetes type 2 – Evidence on routine monitoring of blood glucose. 2010. Available from: www.cks.nhs.uk (Accessed Nov, 2010).
  2. Clar C, Barnard K, Cummins E, et al. Self-monitoring of blood glucose in type 2 diabetes: systematic review. Health Technology Assessment 2010:14(12).
  3. Canadian Agency for Drugs and Technologies in Health. Systematic review of use of blood glucose test strips for the management of diabetes mellitus. Ottawa (ON): The Agency; 2009. Available from: www.cadth.ca/media/pdf/BGTS_SR_Report_of_Clinical_Outcomes.pdf (Accessed Nov, 2010).
  4. O’Kane M, Bunting B, Copeland M, Coates VE. Efficacy of self monitoring of blood glucose in patients with newly diagnosed type 2 diabetes (ESMON study): randomised controlled trial. BMJ 2008;336:1174-7.
  5. NZHIS. Pharmaceutical warehouse. 2010.
  6. NHS Diabetes. Self monitoring of blood glucose in noninsulin-treated Type 2 diabetes: a report prepared by an NHS Diabetes Working Group. March 2010. Available from: www.diabetes.nhs.uk (Accessed Nov, 2010).
  7. British National Formulary (BNF). London BMJ Group, 2010.
  8. Davis WA, Bruce DG, Davis TME. Is self-monitoring of blood glucose appropriate for all type 2 diabetic patients? The Fremantle Diabetes Study. Diabetes Care, 2006;29(8):1764-70.