Poor Specificity of Fasting Plasma Glucose Cut-Off Values in Ruling Out Glucose Intolerance: The Complementary Usefulness of OGTT

Abstract

Introduction: With the objective to assess the diagnostic power of the ADA criteria in detecting glucose intolerance, we studied 654 patients by performing an oral glucose tolerance test (OGTT).

Material and Methods: The design required computing sensitivity, specificity and predictive values for different cut-off levels of fasting plasma glucose (FPG). The patients were recruited in an outpatient facility of a General Internal Medicine department affiliated to a Medical School.

Results: Lowering the threshold from 7.0 to 6.1, 5.6, 5.0 and 4.4 mmol/l (126 to 110, 100, 90 and 80 mg/dl) respectively, resulted in a progressive fall in specificity (99.6, 91.6, 76.0, 45.3 and 15.8%) combined to a rise in sensitivity (8.6, 30.7, 56.4, 76.4 and 92.9%). Two subjects with FPG <5.0 mmol/l were diabetic. At the lowest FPG of 4.4 mmol/l the percentage of glucose intolerant patients by OGTT was still 11% while at 6.1 mmol/l the false positive rate was 50%.

Discussion: The simple screening based on FPG alone, as suggested by ADA, is ineffective, not detecting an unacceptable number of subjects with glucose intolerance, and conveys the high cost of working up an excessively large number of false positives. Only the OGTT represents the effective screening procedure.

OGTT - glucose intolerance - diagnosis

References

• 1 Alberti G, Zimmet PZ, Shaw J, Bloomgarden Z, Kaufman F, Silink M. Consensus Workshop Group. Type 2 diabetes in the young: the evolving epidemic: the international diabetes federation consensus workshop.  Diabetes Care. 2004;  27 1798-1811
• 2 Alberti KG, Zimmet PZ. Definition, diagnosis and classification of diabetes mellitus and its complications. Part 1: diagnosis and classification of diabetes mellitus provisional report of a WHO consultation.  Diabet Med. 1998;  15 539-553
• 3 Barzilay JI, Spiekerman CF, Wahl PW, Kuller LH, Cushman M, Furberg CD. et al . Cardiovascular disease in older adults with glucose disorders: comparison of American Diabetes Association criteria for diabetes mellitus with WHO criteria.  Lancet. 1999;  354 622-625
• 4 Carnevale Schianca GP, Rossi A, Sainaghi PP, Maduli E, Bartoli E. The significance of impaired fasting glucose versus impaired glucose tolerance: importance of insulin secretion and resistance.  Diabetes Care. 2003;  26 1333-1337
• 5 Chiasson JL, Josse RG, Gomis R, Hanefeld M, Karasik A, Laakso M. STOP-NIDDM Trail Research Group: Acarbose for prevention of type 2 diabetes mellitus: the STOP-NIDDM randomised trial.  Lancet. 2002;  359 2072-2077
• 6 Crepaldi G, Belfiore F, Bosello O, Caviezel F, Contaldo F, Enzi G. et al . Italian Consensus Conference; overweight, obesity and health (ICC S.O.S. 1991).  Recenti Prog Med. 1991;  82 417-434
• 7 Davidson MB, Landsman PB, Alexander CM. Lowering the criterion for impaired fasting glucose will not provide clinical benefit.  Diabetes Care. 2003;  26 3329-3330
• 8 Davidson MB. Counterpoint: the oral glucose tolerance test is superfluous.  Diabetes Care. 2002;  25 1883-1885
• 9 DECODE Study Group, European Diabetes Epidemiology Group . Is the current definition for diabetes relevant to mortality risk from all causes and cardiovascular and noncardiovascular diseases?.  Diabetes Care. 2003;  26 688-696
• 10 DeFronzo RA, Ferrannini E, Simonson DC. Fasting hyperglycemia in non-insulin-dependent diabetes mellitus: contributions of excessive hepatic glucose production and impaired tissue glucose uptake.  Metabolism. 1989;  38 387-395
• 11 Expert Committee on the Diagnosis and Classification of Diabetes Mellitus . Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus.  Diabetes Care. 1997;  20 1183-1197
• 12 Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults . Executive Summary of The Third Report of The National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, And Treatment of High Blood Cholesterol In Adults (Adult Treatment Panel III).  JAMA. 2001;  285 2486-2497
• 13 Ferrannini E, Bjorkman O, Reichard Jr GA, Pilo A, Olsson M, Wahren J. et al . The disposal of an oral glucose load in healthy subjects. A quantitative study.  Diabetes. 1985;  34 580-588
• 14 Ferrannini E. Insulin resistance versus insulin deficiency in non-insulin-dependent diabetes mellitus: problems and prospects.  Endocr Rev. 1998;  19 477-490
• 15 Festa A, D’Agostino Jr R, Hanley AJ, Karter AJ, Saad MF, Haffner SM. Differences in insulin resistance in nondiabetic subjects with isolated impaired glucose tolerance or isolated impaired fasting glucose.  Diabetes. 2004;  53 1549-1555
• 16 Genuth S, Alberti KG, Bennett P, Buse J, Defronzo R, Kahn R. et al . Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Follow-up report on the diagnosis of diabetes mellitus.  Diabetes Care. 2003;  26 3160-3167
• 17 Grundy SM, Brewer Jr HB, Cleeman JI, Smith Jr SC, Lenfant C. American Heart Association; National Heart, Lung, and Blood Institute: definition of metabolic syndrome: report of the National Heart, Lung, and Blood Institute/American Heart Association conference on scientific issues related to definition.  Circulation. 2004;  109 433-438
• 18 Hanefeld M, Temelkova-Kurktschiev T, Schaper F, Henkel E, Siegert G, Koehler C. Impaired fasting glucose is not a risk factor for atherosclerosis.  Diabet Med. 1999;  16 212-218
• 19 Knowler WC, Barrett-Connor E, Fowler SE, Hamman RF, Lachin JM, Walker EA. et al . Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin.  N Engl J Med. 2002;  346 393-403
• 20 Krotkiewski M, Bjorntorp P, Sjostrom L, Smith U. Impact of obesity on metabolism in men and women. Importance of regional adipose tissue distribution.  J Clin Invest. 1983;  72 1150-1162
• 21 Kuhl J, Hilding A, Ostenson CG, Grill V, Efendic S, Bavenholm P. Characterisation of subjects with early abnormalities of glucose tolerance in the Stockholm Diabetes Prevention Programme: the impact of sex and type 2 diabetes heredity.  Diabetologia. 2005;  48 35-40
• 22 National Diabetes Data Group . Classification and diagnosis of diabetes mellitus and other categories of glucose intolerance.  Diabetes. 1979;  28 1039-1057
• 23 Piche ME, Arcand-Bosse JF, Despres JP, Perusse L, Lemieux S, Weisnagel SJ. What is a normal glucose value? Differences in indexes of plasma glucose homeostasis in subjects with normal fasting glucose.  Diabetes Care. 2004;  27 2470-2477
• 24 Reaven GM. Banting lecture 1988. Role of insulin resistance in human disease.  Diabetes. 1988;  37 1595-1607
• 25 Sacks DB, Bruns DE, Goldstein DE, Maclaren NK, McDonald JM, Parrott M. Guidelines and recommendations for laboratory analysis in the diagnosis and management of diabetes mellitus.  Clin Chem. 2002;  48 436-472
• 26 Stern MP, Williams K, Gonzalez-Villalpando C, Hunt KJ, Haffner SM. Does the metabolic syndrome improve identification of individuals at risk of type 2 diabetes and/or cardiovascular disease?.  Diabetes Care. 2004;  27 2676-2681
• 27 Tai ES, Goh SY, Lee JJ, Wong MS, Heng D, Hughes K. et al . Lowering the criterion for impaired fasting glucose: impact on disease prevalence and associated risk of diabetes and ischemic heart disease.  Diabetes Care. 2004;  27 1728-1734
• 28 Tirosh A, Shai I, Tekes-Manova D, Israeli E, Pereg D, Shochat T. et al . Normal fasting plasma glucose levels and type 2 diabetes in young men.  N Engl J Med. 2005;  353 1454-1462
• 29 Tuomilehto J. Point: a glucose tolerance test is important for clinical practice.  Diabetes Care. 2002;  25 1880-1882
• 30 Unwin N, Shaw J, Zimmet P, Alberti KG. Impaired glucose tolerance and impaired fasting glycaemia: the current status on definition and intervention.  Diabet Med. 2002;  19 708-723
• 31 Weyer C, Tataranni PA, Bogardus C, Pratley RE. Insulin resistance and insulin secretory dysfunction are independent predictors of worsening of glucose tolerance during each stage of type 2 diabetes development.  Diabetes Care. 2001;  24 89-94

Correspondence