Tests for diagnosing diabetes mellitus Glucose tolerance test is most sensitive

Abstract

EDITOR, - David R McCance and colleagues state that the two hour plasma glucose, glycated haemoglobin, and fasting plasma glucose concentrations are equivalent predictors of the development of retinopathy and nephropathy.1 They therefore consider all three glycaemic variables to be equivalent for diagnosing diabetes. This conclusion should be viewed with caution. With regard to the sensitivity and specificity of glycaemic variables used, their roles in predicting microangiopathy and diagnosing diabetes need to be clearly distinguished. On the basis of data presented in tables I and II in the authors' paper (table), the oral glucose tolerance test has the highest sensitivity in diagnosing diabetes. View this table: Number (percentage) of patients with values above cut off points in McCance and colleagues' study It would be important to know whether all three glycaemic variables in an individual subject had identical centile positions in the distributions of the variables used. This requirement will be fulfilled if there is a positive linear correlation between the two hour glucose and glycated haemoglobin concentrations in an individual. No evidence can be found about this in McCance and colleagues' paper. This correlation is more likely in patients with poor metabolic control than in those with strict control. If the centile positions of the three glycaemic variables for an individual subject differ this means that the prediction of microangiopathy varies as a function of the glycaemic variables used. The Diabetes Control and Complications Trial Research Group has documented that better glycaemic control can delay the onset and slow the progression of microangiopathy in patients with insulin dependent diabetes mellitus.2 Better control implies early diagnosis and treatment of diabetes. Since the oral glucose tolerance test has the highest sensitivity in detecting patients with impaired glucose homoeostasis it will continue to be the preferred method for diagnosing diabetes. 1. 1.↵1. McCance DR, 2. Hanson RL, 3. Charles MA, 4. Jacobsson LTH, 5. Pettitt DJ, 6. Bennett PH, 7. et al . Comparison of tests for glycated haemoglobin and fasting and two hour plasma glucose concentrations as diagnostic methods for diabetes BMJ 1994;308:1323-8. (21 May.) [OpenUrl][1][Abstract/FREE Full Text][2] 2. 2.↵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 mellitus. N Engl J Med 1993;329:977-86. [OpenUrl][3][CrossRef][4][PubMed][5][Web of Science][6] # Interpreting fasting glucose concentration is tricky {#article-title-4} EDITOR, - David … [1]: {openurl}?query=rft.jtitle%253DBMJ%26rft.stitle%253DBMJ%26rft.issn%253D0007-1447%26rft.aulast%253DMcCane%26rft.auinit1%253DD%2BR%26rft.volume%253D308%26rft.issue%253D6940%26rft.spage%253D1323%26rft.epage%253D8%26rft.atitle%253DComparison%2Bof%2Btests%2Bfor%2Bglycated%2Bhaemoglobin%2Band%2Bfasting%2Band%2Btwo%2Bhour%2Bplasma%2Bglucose%2Bconcentrations%2Bas%2Bdiagnostic%2Bmethods%2Bfor%2Bdiabetes%26rft_id%253Dinfo%253Adoi%252F10.1136%252Fbmj.308.6940.1323%26rft_id%253Dinfo%253Apmid%252F8019217%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [2]: /lookup/ijlink?linkType=ABST&journalCode=bmj&resid=308/6940/1323&atom=%2Fbmj%2F309%2F6953%2F537.atom [3]: {openurl}?query=rft.jtitle%253DNew%2BEngland%2BJournal%2Bof%2BMedicine%26rft.stitle%253DNEJM%26rft.issn%253D0028-4793%26rft.aulast%253DThe%2BDiabetes%2BControl%2Band%2BComplications%2BTrial%2BResea%26rft.auinit1%253D%2B%26rft.volume%253D329%26rft.issue%253D14%26rft.spage%253D977%26rft.epage%253D986%26rft.atitle%253DThe%2BEffect%2Bof%2BIntensive%2BTreatment%2Bof%2BDiabetes%2Bon%2Bthe%2BDevelopment%2Band%2BProgression%2Bof%2BLong-Term%2BComplications%2Bin%2BInsulin-Dependent%2BDiabetes%2BMellitus%26rft_id%253Dinfo%253Adoi%252F10.1056%252FNEJM199309303291401%26rft_id%253Dinfo%253Apmid%252F8366922%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [4]: /lookup/external-ref?access_num=10.1056/NEJM199309303291401&link_type=DOI [5]: /lookup/external-ref?access_num=8366922&link_type=MED&atom=%2Fbmj%2F309%2F6953%2F537.atom [6]: /lookup/external-ref?access_num=A1993LY58700001&link_type=ISI