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APPENDIX M: CLINICAL DEFINITION AND DIAGNOSTIC
TESTS

The prospective diabetes screening and management programme shall follow the guidelines
in the latest Hong Kong Reference Framework for Diabetes Care for Adults in Primary Care
Settings (Appendix C). In particular, the guidelines stipulate that considerations for diabetes
screening follow three general rules of thumb, namely any individual i) age 45 years old and
above; or ii) with risk factors for DM, such as family history or obesity; or iii) with symptoms or
signs of DM should be screened (FHB, 2020). Under this framework, clinical definition
and diagnostic requirements are detailed for hyperglycaemia, including the three
tests, namely fasting plasma glucose (FPG); glycated haemoglobin (HbA1c); and oral glucose
tolerance test (OGTT) (see Box 1). Table 1 illustrates the respective diagnostic cut-offs for
detecting DM or pre-diabetes which adopt the same clinical ranges as the WHO criteria.

Box 1

Types of tests for diagnosis of diabetes mellitus

Types of tests for diabetes mellitus
Glycated haemoglobin test (HbA1c) measures a non-fasting blood
sugar level and provides the average blood sugar level for the past two or
three months. The result reflects the percentage of blood sugar attached to
haemoglobin (oxygen carrying protein in red blood cells).

Fasting plasma glucose test (FPG) requires fasting overnight and
measures the fasting blood sugar level.
Oral glucose tolerance test (OGTT) requires fasting overnight and
measures the fasting blood sugar level. Afterwards, ingestion of a sugary
liquid is required, and blood sugar levels are tested for the next two hours.

Table 1

Reference Frameworks for Diabetes Classifications
Hong Kong Reference Framework WHO Classification of Diabetes
for Diabetes Care (2018) Mellitus (2019)
Pre-diabetes • FG 6.1–6.9mmol/L • FG 6.1–6.9mmol/L
Impaired Fasting • OGTT<7.8mmol/L • OGTT<7.8mmol/L
Glucose
Pre-diabetes • FG<7.0 mmol/L • FG<7.0 mmol/L
Impaired Glucose • OGTT≥7.8 and 11.0 mmol/L • OGTT≥7.8 and 11.0 mmol/L
Tolerance
Diabetes • Fasting plasma glucose≥7.0 • Fasting plasma glucose≥7.0
Hyperglycaemia mmol/L mmol/L
• Glycated haemoglobin≥6.5% • Glycated haemoglobin≥6.5%
• Oral glucose tolerance test • Oral glucose tolerance test
≥11.1mmol/l ≥11.1mmol/l

Source: FHB, 2018

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