by Dr. Adele Visser

Overview

Diabetes mellitus (DM) is a group of metabolic disorders which affects carbohydrate metabolism, characterized by hyperglycaemia due to glucose under-utilization and over-production. On the 14th of November, we celebrate World Diabetes Day, to raise awareness of this group of disorders to so drive prevention, early diagnosis and treatment.

Revised diagnostic criteria were established in 1997 to improve on the early identification of patients at risk of retinopathy and nephropathy.

Diagnostic criteria by the American Diabetes Association (ADA)ζ
(As established by presence of any one of the following)
1. HbA1c ≥ 6.5%.
2. Fasting£ glucose ≥ 7.9 mmol/L.
3. 2-hour plasma glucose ≥ 11.1 mmol/L during a OGTT*.
4. Symptoms of hyperglycaemia and a casual (non-fasting) plasma glucose ≥ 11.1 mmol/L.

ζ In the absence of unequivocal hyperglycaemia, repeat testing should be performed.
£ No caloric intake for at least 8 hours.
* Oral Glucose Tolerance Test using WHO-prescribed protocol of 75 g anhydrous glucose in water.
€ Include polyuria, polydipsia and unexplained weight-loss.

Various assays are used both in the acute and chronic setting to allow for the early detection of complications due to DM.

Analyte Measurement principle Interpretation
Ketone testing Acetoacetate, acetone and β-hydroxybutyric acid with variation in sensitivity to each depending on test. Home monitoring of ketones in blood or urine should only be utilized as adjunct to formal diagnosis.
Urine ketone bodies should not be used in the diagnosis or monitoring of a Diabetic ketoacidotic coma (DKA).
HbA1c Glycated portion of haemoglobin A molecule representing glycaemic control over 3 months. Should be routinely performed in monitoring glycaemic control with ADA recommending levels ‹ 7% in non-pregnant adults as aim.
Testing biannually or quarterly following changing treatment regimens.
Values may be affected by the presence of haemoglobin variants or haemoglobinopathies.
eAG Estimated average glucose as extrapolated calculation from HbA1c measurement. Additional marker in evaluation of glycaemic control.
Albuminuria (previously microalbuminuria) Urinary albumin levels at levels below nephrotic threshold.
Various units used, however threshold remains at 30.
Annual testing indicated irrespective of symptoms.
Concentrations ≥ 30 mg/L is considered a risk factor for cardiovascular events.

Routine use of genetic markers, autoimmune markers, insulin and its precursors or insulin antibodies is not advocated in current guidelines, and their use is restricted to specific clinical indications.

  1. Sacks,D.B et al. 2011. Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus. Diabetes Care. 34:e61-e99.
  2. American Diabetes Association. 2021. Glycemic Targets: Standards of Medical Care in Diabetes – 2021. Diabetes Care Supplement 1:S73-84 https:doi.org/10.2337/dc21-S006.