Clinical Case Scenario: Type 2 Diabetes with Hyperglycemia on Metformin
Patient Presentation
A 58-year-old patient with type 2 diabetes presents with persistent hyperglycemia despite taking metformin 2000 mg daily, along with lisinopril for hypertension and atorvastatin for dyslipidemia. Recent labs show HbA1c of 8.9% and fasting blood glucose of 210 mg/dL. The patient denies polyuria, polydipsia, or unintentional weight loss, and appears well-nourished without signs of volume depletion or ketosis.
Initial Assessment and Risk Stratification
The severity of hyperglycemia determines the urgency and type of treatment intensification needed:
For HbA1c 8.5-9.9% without symptoms: Add a second agent to metformin, choosing from sulfonylureas, TZDs, DPP-4 inhibitors, GLP-1 receptor agonists, SGLT2 inhibitors, or basal insulin 1
For HbA1c ≥10% or blood glucose ≥300-350 mg/dL with symptoms: Strongly consider initiating basal insulin immediately, as this reflects more severe insulin deficiency 1, 2
For catabolic features (weight loss, ketonuria, hypertriglyceridemia): Insulin therapy is mandatory and must be started immediately 1, 2
Treatment Algorithm for This Patient (HbA1c 8.9%)
Step 1: Continue Metformin and Add Second Agent
Since this patient has HbA1c <10% without severe symptoms, adding basal insulin to metformin is the most effective next step for achieving glycemic control while minimizing complexity. 2
Alternative options include:
- Sulfonylureas (cost-effective but increase hypoglycemia and weight gain risk) 1
- GLP-1 receptor agonists (reduce weight, lower hypoglycemia risk, but more expensive and injectable) 1
- DPP-4 inhibitors (weight neutral, low hypoglycemia risk, but less potent) 1
- SGLT2 inhibitors (cardiovascular benefits, weight loss, but genitourinary side effects) 1
Step 2: Basal Insulin Initiation Protocol
Start with long-acting insulin analog (glargine or detemir) at 0.2 units/kg/day or 10 units once daily, whichever is lower, given at bedtime. 1, 2
Long-acting analogs (glargine, detemir) are preferred over NPH insulin because they cause less overnight hypoglycemia and possibly slightly less weight gain, though they are more expensive. 1, 2
Detemir typically requires higher average unit requirements than glargine (approximately 20-30% more units). 1, 2
Step 3: Titration Strategy
Titrate basal insulin by 2-3 units every 3 days based on fasting blood glucose until target of 80-130 mg/dL is achieved. 2
Continue metformin during insulin initiation, as this combination decreases weight gain, lowers total insulin dose requirements, and reduces hypoglycemia compared to insulin alone. 3
Patient Education Requirements
Before initiating insulin, provide comprehensive education on: 1, 2
- Glucose monitoring: Check fasting glucose daily before breakfast to guide basal insulin titration 2
- Insulin injection technique: Proper subcutaneous administration using shortest needles (4-mm pen or 6-mm syringe needles) to avoid intramuscular injection 3
- Insulin storage: Keep unopened vials refrigerated; opened vials can be kept at room temperature for 28 days 1
- Hypoglycemia recognition and treatment: Symptoms include shakiness, sweating, confusion; treat with 15g fast-acting carbohydrates 1, 2
- Site rotation: Rotate injection sites to prevent lipohypertrophy, which distorts insulin absorption 3
- Sick day rules: Continue basal insulin during illness; monitor glucose more frequently 1
Monitoring and Follow-Up
Reassess glycemic control after 3 months of combination therapy: 1
- If HbA1c target achieved (<7-7.5%): Continue current regimen with ongoing monitoring
- If HbA1c remains elevated despite optimized basal insulin: Consider adding prandial insulin (rapid-acting analogs before meals) or switching to GLP-1 receptor agonist added to basal insulin 1, 2, 4
The majority of type 2 diabetes patients can be successfully managed with basal insulin alone; prandial insulin is needed only when progressive β-cell dysfunction occurs. 1
Critical Pitfalls to Avoid
Do not use sliding-scale insulin alone as primary therapy—basal-bolus regimens provide superior glycemic control. 2, 5, 6
Do not abruptly discontinue metformin when starting insulin, as this causes rebound hyperglycemia. 3
Avoid metformin if eGFR <30 mL/min/1.73 m² due to lactic acidosis risk; reduce dose if eGFR 30-45 mL/min/1.73 m². 1, 7
Do not delay insulin initiation in symptomatic patients or those with very high glucose levels (>300 mg/dL), as early intervention prevents metabolic decompensation. 1, 2
Warn patients against excessive alcohol intake while on metformin, as alcohol potentiates the effect on lactate metabolism and increases lactic acidosis risk. 7
Cardiovascular Risk Management
Comprehensive cardiovascular risk reduction must remain a major focus alongside glycemic control. 1
Continue lisinopril and atorvastatin as these address hypertension and dyslipidemia, which are critical cardiovascular risk factors in diabetes. 1