Blood Tests Before Starting Nicotine Replacement Therapy
No specific blood tests are required before initiating nicotine replacement therapy (NRT) in patients with diabetes or cardiovascular disease, as NRT does not necessitate laboratory monitoring for safe use. However, baseline assessment of cardiovascular and metabolic status is prudent to optimize overall management during smoking cessation.
Why No Mandatory Pre-NRT Blood Tests
NRT is safer than continued smoking: Clinical trials demonstrate that nicotine replacement therapy does not increase cardiovascular risk even in patients with underlying stable coronary disease, and the risks of NRT are substantially outweighed by the benefits of smoking cessation 1.
Nicotine from NRT differs from smoking: The cardiovascular effects of nicotine are more intense when delivered rapidly by cigarette smoking compared to the slower delivery by transdermal patches or gum, and NRT does not increase blood coagulability (a major risk factor for acute cardiovascular events) unlike cigarette smoking 1.
No drug-specific monitoring needed: Unlike many medications, nicotine patches and gum do not require baseline laboratory assessment for hepatic or renal function, as nicotine metabolism occurs primarily through liver enzymes (CYP2A6, UGT, and FMO) without necessitating dose adjustments based on laboratory values 2.
Recommended Baseline Assessment for Patients with Diabetes
While not required for NRT safety, the following tests optimize diabetes management during smoking cessation:
Essential Tests for Diabetes Monitoring
Hemoglobin A1c: Should be measured at least twice yearly if meeting treatment goals, or quarterly if therapy has changed or targets are not being met 3, 4.
Fasting plasma glucose: Useful for diabetes diagnosis and monitoring, defined as ≥126 mg/dL (7.0 mmol/L) for diabetes diagnosis 5.
Serum creatinine with estimated GFR: Essential for assessing baseline renal function in all patients with type 2 diabetes 3.
Urine albumin-to-creatinine ratio: Should be performed annually in all patients with type 2 diabetes 3, 4.
Additional Considerations
Lipid profile: Should include total cholesterol, HDL, LDL, and triglycerides, with targets of LDL <100 mg/dL (further reduction to <70 mg/dL is reasonable) in patients with cardiovascular disease 5, 6.
Blood pressure: Should be measured at each visit, with targets <140/85 mm Hg for patients with diabetes 5, 3.
Recommended Baseline Assessment for Patients with Cardiovascular Disease
Core Laboratory Tests
Lipid profile: Patients with peripheral artery disease and diabetes should have LDL-C lowered to <1.8 mmol/L (<70 mg/dL) or by ≥50% when the target cannot be reached 5.
Fasting blood glucose and A1c: To screen for undiagnosed diabetes, as diabetes is defined by A1c ≥6.5%, fasting plasma glucose ≥126 mg/dL, or 2-hour plasma glucose ≥200 mg/dL during oral glucose tolerance test 5.
Comprehensive metabolic panel: Assesses kidney function (creatinine, eGFR), liver function (AST, ALT), and electrolyte balance 4.
Complete blood count: Screens for anemia and other blood disorders 4.
Cardiovascular-Specific Monitoring
Serum creatinine with eGFR: Chronic kidney disease staging is important, as stages 3-5 (GFR <60 mL/min/1.73 m²) indicate increased cardiovascular risk 5.
Electrocardiogram: Recommended in adults if clinically indicated 3.
Clinical Context: Why These Tests Matter
People with diabetes face unique challenges with smoking cessation: After acute coronary syndrome, patients with diabetes who smoke are less likely to quit compared to those without diabetes (35.1% vs 42.6% cessation at 1 year), highlighting the need for comprehensive secondary prevention 7.
Cardiac rehabilitation improves outcomes: Among people with diabetes, cardiac rehabilitation attendance is a positive predictor of smoking cessation success 7.
Common Pitfalls to Avoid
Do not delay NRT initiation waiting for laboratory results: The cardiovascular risks of continued smoking far exceed any theoretical concerns about NRT, even in patients with active cardiovascular disease 1.
Do not use single lipid measurements for treatment decisions: Abnormal results should be confirmed by repeated sampling on a separate occasion, with the average of both results used for risk assessment 6.
Do not rely solely on A1c in certain conditions: In patients with increased red blood cell turnover (sickle cell disease, pregnancy, hemodialysis, recent blood loss/transfusion, erythropoietin therapy), use plasma glucose criteria instead 3.
Do not overlook medication adjustments: Consider adjusting concomitant medications such as insulin or sulfonylureas to minimize hypoglycemia risk when initiating comprehensive smoking cessation programs 3.