Diagnosis Modalities

Michelle Renee Campbell; Masih Shokrani

doi:10.29074/ascls.29.2.111

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Michelle Renee Campbell, MLS (ASCP)
1. Medical Laboratory Sciences Program, Northern Illinois University, DeKalb, IL
Masih Shokrani, Ph.D. MT (ASCP)⇑
1. Medical Laboratory Sciences Program, Northern Illinois University, DeKalb, IL

Address for Correspondence: Masih Shokrani, Ph.D. MT (ASCP), Associate Professor, Medical Laboratory Sciences Program, Northern Illinois University, DeKalb, IL, 60115-2828, 815-753-6323, mshokrani{at}niu.edu

Discuss the use of fasting blood glucose, HbA1c and oral glucose tolerance testing for screening and diagnosis of diabetes mellitus.
Differentiate screening procedures for type 1 and type 2 diabetes mellitus.
Describe testing for gestational diabetes.
Identify various autoantibodies and their association with type 1 diabetes mellitus.

Extract

INTRODUCTION Proper testing for both type 1 and 2 diabetes mellitus is vital in the diagnostic process, monitoring the progression of the disease and determining the efficacy of treatment. According to the American Diabetes Association (ADA), in the absence of indisputable hyperglycemia, the diagnosis of diabetes mellitus should always be confirmed with repeat testing.¹ Timing of testing, as well as the specific tests ordered, may vary. The same basic tests, however, are utilized across most facilities.² Fasting plasma glucose, hemoglobin A1c (HbA1c) and oral glucose tolerance testing (OGTT) are all recommended for both screening and diagnosis of diabetes mellitus.²

Various Testing Procedures The test often used to detect diabetes mellitus is a measurement of fasting blood glucose levels. After the patient has fasted overnight (at least 8 hours), blood sugar levels are measured using a methodology similar to that for random blood sugar levels. Fasting blood sugar levels of less than 100 mg/dL (~5.5 mmol/L) are normal. Levels between 100 and 125 mg/dL (~5.5-6.9 mmol/L) are considered prediabetic; levels above 125 mg/dL (~6.9 mmol/L) are considered diabetic in nature. Results hinge on the patient's compliance with fasting instructions prior to testing.³

HbA1c levels need to be measured as well. HbA1c is measured in percentages and reflects the average blood glucose levels over the past 3 months. HbA1c may be measured at any time, regardless of the last meal ingested.⁴ An International Expert Committee and the American Diabetes Association have declared hemoglobin A1c measurements accurate enough to be used for the…

ABBREVIATIONS: HbA1c - Hemoglobin A1c, ADA - American Diabetes Association, OGTT - Oral glucose tolerance test, G6P - Glucose-6-phosphate ICA - Islet cell antibody, GADA - Glutamic acid decarboxylase antibody, IA-2A - Islet antigen-2 antibody, IAA- Insulin autoantibody

Discuss the use of fasting blood glucose, HbA1c and oral glucose tolerance testing for screening and diagnosis of diabetes mellitus.
Differentiate screening procedures for type 1 and type 2 diabetes mellitus.
Describe testing for gestational diabetes.
Identify various autoantibodies and their association with type 1 diabetes mellitus.