Abnormal Glucose Tolerance

Overview

Abnormal glucose tolerance refers to impaired regulation of blood glucose levels, usually detected by oral glucose tolerance testing (OGTT). It includes:

• Impaired fasting glucose (IFG): fasting plasma glucose 100–125 mg/dL (5.6–6.9 mmol/L).

• Impaired glucose tolerance (IGT): 2-hour OGTT 140–199 mg/dL (7.8–11.0 mmol/L).

• Diabetes mellitus (DM): fasting ≥126 mg/dL or 2-hour OGTT ≥200 mg/dL.

It represents an intermediate stage between normal glucose and diabetes, associated with insulin resistance and increased risk of progression to type 2 diabetes and cardiovascular disease.

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Treatment Options

1. Lifestyle Modification (First-Line)

• Dietary changes: reduce refined carbohydrates, saturated fats, and increase whole grains, fruits, vegetables.

• Weight reduction: 5–10% weight loss can significantly improve glucose tolerance.

• Physical activity: at least 150 minutes/week of moderate exercise (e.g., brisk walking).

• Smoking cessation and limiting alcohol.

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2. Pharmacological Therapy

(Used when lifestyle modification is insufficient or high risk of progression to diabetes)

• Metformin

  • First-line pharmacologic option.

  • Dose: Start 500 mg PO once daily with meals, increase to 850–1000 mg BID as tolerated.

  • Useful especially in overweight patients, those <60 years, or women with prior gestational diabetes.

• Acarbose (α-glucosidase inhibitor)

  • Dose: 25–100 mg PO TID with meals.

  • Slows carbohydrate absorption, blunts postprandial glucose rise.

• Thiazolidinediones (e.g., pioglitazone)

  • Dose: 15–30 mg PO once daily, titrated up to 45 mg.

  • Improves insulin sensitivity, but limited by weight gain, edema, and CV risk.

• GLP-1 receptor agonists (e.g., liraglutide, semaglutide)

  • Shown to reduce progression to diabetes in obese/high-risk individuals.

  • Liraglutide: start 0.6 mg SC daily → titrate to 1.2–1.8 mg daily.

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3. Management of Associated Risks

• Hypertension: treat with ACE inhibitors (e.g., ramipril 5–10 mg PO daily).

• Dyslipidemia: statin therapy (e.g., atorvastatin 20–40 mg PO daily).

• Antiplatelet therapy: consider low-dose aspirin in high cardiovascular risk patients.

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Supportive & Monitoring Measures

• Regular blood glucose monitoring (fasting, postprandial, HbA1c).

• Annual screening for diabetes complications (retinopathy, nephropathy, neuropathy).

• Counseling and patient education on lifestyle and adherence.

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Key Notes

• Abnormal glucose tolerance is reversible with early lifestyle and pharmacological intervention.

• Metformin is the most widely used and evidence-based drug for prevention of progression to diabetes.

• Patients require long-term follow-up, as cardiovascular risk remains elevated even if glucose normalizes.