Introduction:
Diabetes is a prevalent metabolic disorder characterized by
elevated blood sugar levels. The accurate diagnosis of diabetes involves a
combination of clinical assessments, medical history, and specific laboratory
tests. This guide outlines the essential investigations and their respective
results used for diagnosing diabetes mellitus.
1. Fasting Blood Glucose Test (FBG) :
- Normal Range:
Less than 100 mg/dL (5.6 mmol/L)
- Prediabetes
Range: 100-125 mg/dL (5.6-6.9 mmol/L)
- Diabetes Range:
Equal to or greater than 126 mg/dL (7.0 mmol/L) on two separate tests
2. Oral Glucose Tolerance Test (OGTT) :
- Normal Range:
Less than 140 mg/dL (7.8 mmol/L) after 2 hours
- Prediabetes
Range: 140-199 mg/dL (7.8-11.0 mmol/L) after 2 hours
- Diabetes Range:
Equal to or greater than 200 mg/dL (11.1 mmol/L) after 2 hours
3. Hemoglobin A1c (HbA1c) :
- Normal Range:
Less than 5.7%
- Prediabetes
Range: 5.7-6.4%
- Diabetes Range:
Equal to or greater than 6.5%
4. Random Blood Glucose Test :
- Diabetes
Diagnosis: Equal to or greater than 200 mg/dL (11.1 mmol/L) accompanied by
classic hyperglycemic symptoms
Additional Investigations and Considerations:
- Glycated Albumin :
Offers a short-term reflection of glycemic control compared to HbA1c.
- C-peptide and
Insulin Levels : Aids in determining if diabetes results from insufficient
insulin production.
- Autoantibody
Testing : Vital for Type 1 diabetes diagnosis due to autoantibodies against
insulin- producing cells.
- Lipid Profile:
Assessing lipid levels is crucial due to the association between diabetes and dyslipidemia.
- Kidney Function
Tests: Reflects diabetes' impact on kidney function; includes serum creatinine
and estimated glomerular filtration rate (eGFR) tests.
- Blood Pressure
Measurement: Regular monitoring as hypertension often accompanies diabetes.
- Eye Examination:
Essential for diabetic retinopathy assessment, a diabetes-related eye
complication.
- Foot Examination:
Regular foot exams are necessary due to diabetes-related neuropathy and foot ulcers.
