Service Specification

Transcription

1 Service Specification Glucose Tolerance Testing Date: February 2011 Document Reference: Service Specification (V1.0)

2 Contents: Section Page 1 Definition of service 3 2 Training 3 3 Reporting / Monitoring 3 2

3 1 Definition of Service 1.1 Aims & Objectives The service will ensure that all people in whom there is doubt regarding the diagnosis of diabetes will have access to a Glucose Tolerance Test. 1.2 Service Outline The fasting plasma glucose is the preferred test for the diagnosis of diabetes mellitus (DM). The Glucose Tolerance Test is used to confirm the diagnosis of diabetes when it cannot be established by either random or fasting glucose alone. The diagnosis of DM should not be made on the basis of a single raised plasma glucose in the absence of symptoms. The oral glucose tolerance test (GTT) is used when analysis of fasting and/or random glucose levels have not provided a clear diagnosis. 75g of anhydrous glucose (or its equivalent) in a final volume of 300 ml is used as recommended by WHO. A GTT is indicated if: a) there is impaired fasting glycaemia, (fasting plasma glucose >6.0 mmol/l, but <7.0 mmol/l) b) previous history of gestational diabetes The service outline is as per the practice protocol and NICE Guidance Appendix A outlines the service in greater detail, including the equipment, procedure, and interpretation of the service. 1.3 Client Group The service will only be provided to those patients identified as possibly having diabetes. It is not the intention that this service will provide a screening programme for diabetes. 2 Training / Workforce / Staffing There are no specific requirements for training over and above the general requirement set out in the Basket of Services specification. 3 Reporting / Monitoring The service provider will not be required to submit activity or audit reports to the PCT. This specification should be read in conjunction with main Basket of Services specification. 3

4 Appendix A The patient should fast from 10 pm. the previous evening, to give a minimum 10 hour fasting period, and not eat or drink anything other than water, until the test is completed. Equipment For use in GP surgeries a) Glucose - dissolve 1 packet of dextrose (82.5g glucose monohydrate) in 250 ml water, this gives a final volume of 300 ml. This is equivalent to 75g anhydrous glucose. The dextrose is lemon flavoured to make it more palatable. Chemical Pathology, RDH obtains the glucose from pharmacy and provides supplies for GPs. Note: Glucose BP is glucose monohydrate. b) Lucozade may be used as an alternative. 410mL of Lucozade Energy Original (containing70kcal/100ml glucose) is equivalent to 75g anhydrous glucose. Please note that before May 2009 the formulation of Lucozade Energy Original contained 73kcal/100mL glucose and therefore only 394mL was required to deliver 75g glucose. It may be necessary to check the back of the packaging to confirm which formulation is in the bottle or can. c) Specimen tubes required Each test requires two fluoride/oxalate tubes. PROCEDURE The patient may drink additional water during the test and must be seated quietly throughout the test. Smoking is not permitted during the test. The GTT procedure is described below. Samples must be clearly labelled with patient name, date and time, e.g am. GTT Procedure TIME Fasting sample BLOOD SAMPLE for glucose Minimum volume 1 ml fluoride/oxalate tube 0 hours Give glucose solution to be drunk within 5 minutes or Lucozade (quantities as above) 2 hours sample Minimum volume 1 ml fluoride/oxalate tube 4

5 INTERPRETATION OF GLUCOSE TOLERANCE TEST Normal Both of the following criteria must be met 1) Fasting glucose 6.0 mmol/l 2) 2 hour GTT glucose <7.8 mmol/l Diagnostic Criteria for Diabetes Mellitus Results from the GTT are sufficient to make a diagnosis of Diabetes where the following is met: a) Fasting glucose 7.0 mmol/l or b) 2 hour glucose 11.1 mmol/l Diagnostic Criteria for Impaired Glucose Tolerance Where following criteria is met: 2 hour GTT glucose > 7.8 mmol/l but < 11.1 mmol/l Diagnostic Criteria for Impaired Fasting Glycaemia Where following criteria is met: Fasting glucose >6.0 but <7.0 mmol/l Results of GTT Once the practice has received the results of the GTT the practice is responsible for informing the patient of the outcome within an appropriate time period. A clear plan of care will then be developed jointly between the clinician and the patient with regards to ongoing management. 5