DIABETES MELLITUS [Oral Glucose Tolerance Test - OGTT]The Australian Diabetes Society [MJA vol. 170, 375-378, 1999] diagnostic criteria for diabetes mellitus and its precursors are based on fasting, random or 2 hour post 75g glucose load, venous plasma glucose [VPG] levels as listed below:
Diabetes mellitus
Classical symptoms of thirst and polyuria plus:
Fasting venous plasma glucose [VPG] level of ?7.0mmol/L
and/or
Random or two-hour post 75g load VPG level of ?11.1mmol/L.Where symptoms are absent or atypical, confirm diabetes with standard OGTT; or repeat the fasting or random VPG test on another day.
Impaired glucose tolerance [IGT]
Fasting VPG level of <7.0mmol/L
and
Two-hour post 75g glucose load VPG level of 7.8-11.0mmol/L.IGT indicates increased risk or progression to frank diabetes, and is associated with cardiovascular risk factors.
Impaired fasting glycaemia [IFG]
Fasting VPG level of 6.1-6.9mmol/LIFG is a variable indicator of diabetes, IGT, and vascular risk. Some people with IFG have diabetes.
Gestational Diabetes
Fasting VPG of ?5.5mmol/L
and/or
Two hour post 75g load VPG level of ?8.0mmol/L
OGTT should be repeated 6-8 weeks post partum.
In line with current guidelines OGTT protocol will entail fasting and two hour post 75g glucose load, VPG levels – the previous protocol we used included a one hour VPG level which is no longer required. REQUESTING PRACTITIONERS ARE REMINDED THAT PATIENTS ARE REQUIRED TO MAKE AN APPOINTMENT FOR AN OGTT BY TELEPHONING THE LABORATORY ON 63 343636.
LIPID COMMENTS
The National Heart Foundation of Australia and The Cardiac Society of Australia and New Zealand have recently released “Lipid Management Guidelines 2001” [MJA 2001; 175:S57-S88] based on a review of evidence based literature. Criteria are presented for determining higher absolute risk of developing coronary artery disease; features to consider include clinical factors alone or in combination with lipid level [total cholesterol >6.0mmol/L, LDL-cholesterol >4.0mmol/L, HDL cholesterol <1.0mmol/L] and other laboratory measurements [such as microalbuminuria, renal impairment, glucose intolerance]. No clear lipid levels are given for drug treatment start points but in those in whom treatment is initiated, there are recommended target levels. The PBS eligibility criteria for lipid lowering agents are also a consideration [unfortunately there are currently discrepancies between PBS and NHF guidelines].Our lipid comment provided with reports will now make reference to the new guidelines with respect to target levels alone.
PROSTATE SPECIFIC ANTIGEN [PSA]The Health Insurance Commission now only permit one estimation of PSA per year in the assessment of clinically suspected prostatic disease and four estimations per year for the monitoring of previously diagnosed disease. Please specify on the request form if the patient has known prostatic disease.
VACUTAINER TUBE CHANGESOn the 12th March 2002, we will be changing to BD vacutainer blood tubes, which have different colour codes to our existing tubes.Vacutainer colour guide sheets will be provided when the change over occurs.If you have any queries or comments, please do not hesitate to contact the Pathologists or Practice Manager on 63 34 3636.