Laboratory tests for Screening and Diagnosis of diabetes mellitus

• Fasting plasma glucose (FPG)
• Random plasma glucose (RPG)
• 2hr plasma glucose of an OGTT (2hr PG)
• Capillary blood Glucose (CBG)
• Urinary glucose (UG)

Screening:

• Screening is recommended for all individuals with one or more major risk factors for
developing diabetes mellitus
• FPG is the laboratory test recommended for screening of individuals for diabetes mellitus
• RPG is an alternative test for screening.
• When facilities to do FPG or RPG are not available, CBG and UG are alternatives
screening for patients with classical symptoms of DM.

Diagnosis:

• The term diagnosis refers to confirmation of diabetes in people who have symptoms, or who have had a positive screening test.
• Either FPG or RPG can be used for the confirmation of diagnosis In symptomatic individuals one abnormal plasma glucose measurement in the diabetic range confirms the diagnosis.
• Asymptomatic individuals with a positive screening test (FPG or RPG) need another abnormal plasma glucose measurement on another day for the confirmation of the diagnosis.
• OGTT is not recommended for routine use as a confirmatory test.

Criteria for the diagnosis of Diabetes Mellitus:

• FPG ≥7.0 mmol/l (126 mg/dl). Fasting is defined as no caloric intake for at least 8 h. or
• Symptoms of diabetes plus random plasma glucose concentration ≥11.1 mmol/l (200 mg/dl). Random is defined as any time of day without regard to time since last meal. The classic symptoms of diabetes include polyuria, polydipsia, and unexplained weight loss or
• 2-h postload glucose ≥ 11.1 mmol/l (200 mg/dl) during an OGTT




Baseline laboratory tests in a newlydiagnosed patient with diabetes mellitus


Patients with type 2 DM could have had the disease for 5 – 7 years prior to the diagnosis.
Therefore the following biochemical tests are recommended for all newly diagnosed patients with DM to detect other associated metabolic and microvascular
complications. Baseline biochemical tests for newly diagnosed patients with DM

• Serum electrolytes
• Serum creatinine and estimated GFR (eGFR)
• Lipid profile (preferred) or serum cholesterol
• Urinary protein
• Urinary microalbumin (patients with negative
proteinuria)
• 24 hr urinary protein (patients with overt proteinuria)

Laboratory tests for the follow up of patients with IFG, IGT and DM (impaired glucose regulation and diabetes):

• All patients with IFG alone should be followed up with FPG annually
• All patients with IGT should be followed up with an OGTT annually. Patients diagnosed with DM should be monitored with FPG monthly.
• Glycosylated Haemoglobin (HbA1C) is recommended for follow up once in three months until satisfactory glycaemic control is achieved.
• HbA1C is recommended at least once in six months in patients who have achieved optimal control.
• Annual microalbumin (patients with negative proteinuria) and lipid profile testing are recommended for patients with DM.

Laboratory tests in the management of patients with metabolic complications of diabetes mellitus

Metabolic complications of DM

• Diabetic ketoacidotic coma
• Hyperosmolar nonketotic coma
• Hypoglaycaemia

Recommended laboratory tests in patients with metabolic complications
• Capillary Blood glucose
• Random plasma glucose (If CBG is abnormal)
• Urinary glucose
• Urinary ketone bodies
• Serum electrolytes
• Blood urea
• Serum creatinine
• Arterial blood gas analysis


Laboratory tests for Screening, Diagnosis and Management of
Gestational DM:

Selective screening is recommended for women with risk factors for developing GDM.
Risk factors for GDM

• Glycosuria in the 1st trimester
• Glycosuria on two occasions in either the second or third trimester
• Polyhydroamnios, macrosomia, large for gestational age in the current pregnancy
• Previous unexplained stillbirth
• Family history in a first degree relative
• Obesity (BMI>25Kg/m2) at the booking visit
• Age > 35 years
• Previous GDM
• Recurrent miscarriages
• Previous macrosomic baby

2hr postprandial plasma glucose (2hr PPG) following a standard meal at antenatal booking is recommended for screening for GDM.

• All abnormal screening tests should be followed up with an OGTT for confirmation of GDM.
• Pregnant mothers with a negative screening test should be evaluated at 24 -28 weeks of gestation with an OGTT.
• Protocol for OGTT is the same as for non pregnant adults and should be interpreted by an Obstetrician.