1. Chapter Overview
This chapter answers the critical question: “How low should we go?” It balances the benefits of intensive glycemic control (reduced microvascular and long-term cardiovascular complications) against the risks (hypoglycemia and mortality, particularly in high-risk groups).
For the CDE exam, you must master the individualization of targets. The “one size fits all” approach is outdated. You need to know exactly who qualifies for a target of ≤6.5% and who requires a more relaxed target of 7.1%–8.5%.
2. Key Messages (The "Gold Nuggets")
Fundamental Goal: Optimal glycemic control is fundamental to the management of diabetes.
The “Legacy Effect”: Early intensive control has long-lasting benefits. Even if control worsens later, the initial period of tight control reduces long-term complications (microvascular and CV).
Individualization is Mandatory: Glycemic targets should be individualized based on the individual’s frailty, functional dependence, and life expectancy.
A1C Composition: Both fasting plasma glucose (FPG) and postprandial plasma glucose (PPG) contribute to the A1C value.
Clinical Pearl: As A1C gets closer to target (≤7.0%), PPG (post-meal glucose) becomes the dominant contributor. When A1C is high, FPG (fasting) is the main driver.
3. The Evidence: Major Clinical Trials
You may be asked which trial demonstrated specific outcomes.
DCCT (Type 1) & UKPDS (Type 2):
Established that intensive control significantly reduces microvascular complications.
Long-term follow-up revealed the “Metabolic Memory” or “Legacy Effect,” showing significant reductions in CV outcomes and mortality years after the trials ended.
ACCORD (Type 2):
Targeted A1C <6.0% in older patients with long-standing diabetes and CV risk.
Result: Prematurely terminated due to higher mortality in the intensive arm.
Lesson: Tight control may not be safe for high-risk, older individuals with established CVD.
ADVANCE (Type 2):
Targeted A1C ≤6.5%.
Result: Significant reduction in nephropathy (21% reduction). No benefit on mortality/CV events during the trial.
VADT (Type 2):
Targeted A1C reduction of 1.5% in veterans with poor control.
Result: No initial CV benefit, but long-term observational follow-up showed a significantly lower risk of major CV events.
4. Recommended Targets (The "Numbers")
A. A1C Targets
B. Glucose Targets
To achieve an A1C ≤7.0%, patients should aim for:
Fasting/Preprandial PG: 4.0 to 7.0 mmol/L.
2-Hour Postprandial PG: 5.0 to 10.0 mmol/L.
Intensified Targets: If A1C target is not met, consider tighter targets if safe:
Fasting/Preprandial: 4.0 to 5.5 mmol/L.
2-Hour Postprandial: 5.0 to 8.0 mmol/L.
5. Diabetes Canada Clinical Practice Guidelines Recommendations
hese are the “Must Memorize” graded recommendations for the exam.
General Target: In most people with type 1 or type 2 diabetes, an A1C ≤7.0% should be targeted to reduce the risk of microvascular complications and, if implemented early, CV complications.
Grade A, Level 1A (Microvascular); Grade B, Level 3 (CV).
Tighter Target (T2D): In people with type 2 diabetes, an A1C ≤6.5% may be targeted to reduce the risk of CKD and retinopathy, if at low risk of hypoglycemia.
Grade A, Level 1A.
Relaxed Targets: A higher A1C target may be considered to avoid hypoglycemia and over-treatment in specific groups:
Functionally dependent: 7.1%–8.0%.
Recurrent severe hypoglycemia/unawareness: 7.1%–8.5%.
Limited life expectancy: 7.1%–8.5%.
Frail elderly/dementia: 7.1%–8.5%.
Grade D, Consensus for all above.
End of Life: A1C measurement is not recommended. Avoid symptomatic hyperglycemia and any hypoglycemia.
Grade D, Consensus.
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