Pre-Diabetes and Type 2 Diabetes: NAC OSCE Canada Guide
PRE-DIABETES
What is Pre-Diabetes?
Pre-diabetes means your blood sugar is higher than normal but not yet high enough to be called diabetes 1. Think of it as a warning sign—your body is struggling with sugar control, but you can still turn things around.
Causes of Pre-Diabetes
- Insulin resistance: Your body's cells don't respond well to insulin (the hormone that moves sugar from blood into cells)
- Excess body weight: Fat, especially around your belly, makes insulin work less effectively 1
- Physical inactivity: Not exercising worsens insulin resistance 1
- Genetics: Family history of diabetes increases risk 1
- Age: Risk increases after age 40 1
- Previous gestational diabetes (diabetes during pregnancy) 1
- Ethnicity: Higher risk in African Americans, Hispanic/Latino, Native Americans, Asian Americans, Native Hawaiians and Pacific Islanders 1
Important caveat: Asian Americans develop diabetes at lower body weights—about 15 pounds less than other populations 1.
Symptoms of Pre-Diabetes
Here's the tricky part: pre-diabetes usually has NO symptoms 2. This is why screening is so important. You feel completely fine while your body is already developing problems.
Diagnosis of Pre-Diabetes
Screen adults over 45 years old every 3 years, or earlier/more frequently if they have risk factors 3. Use the ADA risk test (score ≥5 indicates high risk) 1.
Diagnostic criteria (any ONE of these):
- Fasting plasma glucose: 5.6–6.9 mmol/L (100–125 mg/dL)
- 2-hour glucose on oral glucose tolerance test: 7.8–11.0 mmol/L (140–199 mg/dL)
- A1C: 5.7–6.4% 4, 2
Once diagnosed, monitor for progression to diabetes at least annually 4.
Management of Pre-Diabetes
Lifestyle modification is the absolute cornerstone—this is non-negotiable and more effective than medication 2, 5, 6.
Lifestyle Changes (First-line for ALL patients):
- Weight loss: Target 5-10% body weight reduction
- Physical activity: 150 minutes/week of moderate exercise
- Diet: Reduce refined carbohydrates, added sugars, sugar-sweetened beverages; emphasize whole, minimally processed foods 7
- Avoid ultra-processed foods 7
Medications (for high-risk patients or when lifestyle fails):
- Metformin: First choice for medication, especially if BMI ≥35, age <60, or history of gestational diabetes 5, 6
- Acarbose: Alternative option 5
- Thiazolidinediones: For very high-risk patients who progress despite intensive lifestyle changes 5
Vitamin D supplementation may reduce progression to diabetes in deficient individuals with high metabolic risk 8, though this is emerging evidence.
TYPE 2 DIABETES
What is Type 2 Diabetes?
Type 2 diabetes accounts for 90-95% of all diabetes 1. Your body has both insulin resistance (cells don't respond to insulin) AND relative insulin deficiency (pancreas doesn't make enough insulin) 1.
Causes of Type 2 Diabetes
- Insulin resistance: Decreased biological response to insulin 1
- Beta cell dysfunction: Pancreas can't produce enough insulin to overcome resistance 9
- Excess body weight/obesity: Most (but not all) patients have overweight or obesity 1
- Abdominal fat distribution: Even normal-weight people with belly fat are at risk 1
- Genetics: Strong family history component 1
- Physical inactivity 1
- Age, ethnicity (same risk factors as pre-diabetes) 1
Symptoms of Type 2 Diabetes
Type 2 diabetes frequently goes undiagnosed for YEARS because hyperglycemia develops gradually 1. Early stages often have no symptoms.
Classic symptoms when present:
- Polyuria (excessive urination)
- Polydipsia (excessive thirst)
- Dehydration
- Unintentional weight loss
- Blurred vision
- Fatigue
Critical pitfall: Even without symptoms, patients are developing macrovascular (heart disease, stroke) and microvascular (kidney, eye, nerve) complications 1.
Diagnosis of Type 2 Diabetes
Screen adults over 45 every 3 years; screen earlier/more frequently with risk factors 3.
Diagnostic criteria (any ONE of these):
- Fasting plasma glucose ≥7.0 mmol/L (126 mg/dL) 3
- 2-hour glucose on oral glucose tolerance test ≥11.1 mmol/L (200 mg/dL)
- A1C ≥6.5%
- Random glucose ≥11.1 mmol/L with symptoms
Note: The fasting glucose threshold was lowered from 7.8 to 7.0 mmol/L to improve sensitivity and catch more cases early 3.
Management of Type 2 Diabetes
Management must address BOTH glucose control AND cardiovascular risk factors (hypertension, dyslipidemia) 10, 6.
Step 1: Lifestyle Modification (Foundation for ALL patients)
- Weight loss: Target 5-10% reduction if overweight/obese 6
- Physical activity: 150 minutes/week moderate exercise
- Diet: Whole foods, minimize ultra-processed foods, refined carbs, added sugars, sugar-sweetened beverages 7
- Limit saturated fat to <10% of energy 7
Protein intake: 1.2-1.6 g/kg/day recommended, but use caution in patients with or at risk for chronic kidney disease 7.
Step 2: Pharmacological Treatment
Use a complications- and comorbidities-centric approach, not just glucose levels 6.
First-line medication choices based on patient profile:
- If cardiovascular disease or high CV risk: GLP-1 receptor agonist or SGLT2 inhibitor with proven CV benefit 6
- If heart failure or chronic kidney disease: SGLT2 inhibitor 6
- If obesity is prominent: GLP-1 receptor agonist (also helps weight loss) 6
- If no specific comorbidities: Metformin is traditional first-line 6
Insulin therapy: Initiate when oral agents fail to achieve glycemic targets or in severe hyperglycemia 6.
Step 3: Glycemic Targets
Strive for tight metabolic control to achieve optimal glucose levels 3. This requires:
- Diabetes education through healthcare team
- Diligent self-monitoring of blood glucose
- Stepwise adjustments in medications 3
Duration of glycemic burden is a strong predictor of adverse outcomes—early aggressive control matters 1.
Step 4: Cardiovascular Risk Management
- Hypertension control: Treat to target 6
- Dyslipidemia management: Statin therapy for most patients 6
- Antiplatelet therapy: Consider in appropriate patients 6
Step 5: Surveillance for Complications
Simple tests to detect preclinical disease are readily available 1. Screen regularly for:
- Retinopathy: Annual eye exams
- Nephropathy: Annual urine albumin and kidney function
- Neuropathy: Annual foot exams
- Cardiovascular disease: Risk assessment
Vaccinations
Adults with diabetes need specific vaccines 6—ensure up-to-date immunizations.
Key Differences: Pre-Diabetes vs Diabetes
| Feature | Pre-Diabetes | Type 2 Diabetes |
|---|---|---|
| Symptoms | Usually NONE [2] | Often none early; classic symptoms later [1] |
| Reversibility | Can revert to normal with lifestyle changes [2,11] | Chronic condition requiring ongoing management |
| Treatment priority | Lifestyle modification first [2,5] | Lifestyle + medications based on comorbidities [6] |
| Monitoring | At least annually [4] | Ongoing with A1C every 3-6 months |
| Complications | Increased CV risk [2] | Macro- and microvascular complications [1] |
NAC OSCE Pearls
For pre-diabetes:
- Emphasize that it's reversible with lifestyle changes 2, 11
- Screen high-risk patients even if asymptomatic
- Lifestyle modification is MORE effective than metformin long-term 2
For type 2 diabetes: