Insulin glargine

What is Insulin glargine?

Insulin glargine is a long-acting synthetic insulin analog that belongs to the class of basal insulin medications. It is designed to provide steady, 24-hour glucose control for people with diabetes mellitus. This medication mimics the body’s natural baseline insulin production and is typically administered once daily via subcutaneous injection.

Uses

• Type 1 diabetes mellitus: Used as basal insulin therapy in combination with rapid-acting insulin to replace the body’s inability to produce insulin
• Type 2 diabetes mellitus: Prescribed when blood sugar cannot be adequately controlled with oral medications, diet, and exercise alone
• Gestational diabetes: May be used during pregnancy when dietary modifications fail to maintain target glucose levels
• Secondary diabetes: Treatment for diabetes caused by pancreatic disease, surgery, or certain medications that affect insulin production
• Diabetic ketoacidosis prevention: Helps prevent this serious complication by maintaining baseline insulin levels in insulin-dependent patients

How it works

Insulin glargine works by binding to insulin receptors on muscle, fat, and liver cells, allowing glucose to enter these tissues and lowering blood sugar levels. Its unique molecular structure causes it to form microprecipitates under the skin after injection, which slowly dissolve and release insulin consistently over 24 hours. This extended release profile helps maintain steady blood glucose levels between meals and overnight without significant peaks.

Side effects

Common side effects:

• Injection site reactions (redness, swelling, itching)
• Hypoglycemia (low blood sugar)
• Weight gain
• Headache
• Upper respiratory tract infections
• Fatigue
• Dizziness
• Nausea

Serious side effects requiring immediate medical attention:

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• Severe hypoglycemia with confusion, seizures, or loss of consciousness
• Severe allergic reactions including difficulty breathing, swelling of face or throat
• Hypokalemia (dangerously low potassium levels)
• Severe injection site reactions with tissue death
• Fluid retention causing swelling in hands, feet, or ankles

Warnings and precautions

• Hypoglycemia risk: Patients with kidney or liver disease, elderly individuals, and those who skip meals face increased risk of dangerous blood sugar drops
• Pregnancy considerations: Generally considered safe during pregnancy (Category B), but insulin requirements may change significantly throughout pregnancy and require close monitoring
• Renal impairment: Patients with kidney disease may require dose adjustments as insulin clearance is reduced, increasing hypoglycemia risk
• Drug switching: Changing between different insulin types or brands requires careful medical supervision and blood glucose monitoring
• Injection rotation: Failure to rotate injection sites can lead to lipodystrophy, affecting insulin absorption and glucose control

Interactions

• Beta-blockers: May mask hypoglycemia symptoms and prolong recovery from low blood sugar episodes
• ACE inhibitors: Can enhance insulin sensitivity and increase hypoglycemia risk, requiring dose adjustments
• Corticosteroids: Reduce insulin effectiveness by increasing insulin resistance, often requiring higher insulin doses
• Alcohol: Can cause delayed hypoglycemia several hours after consumption, especially when combined with inadequate food intake
• Salicylates (aspirin): High doses may enhance insulin action and increase hypoglycemia risk
• Thyroid hormones: May increase insulin requirements by raising blood glucose levels
• Chromium supplements: May enhance insulin sensitivity, potentially requiring dose reductions to prevent hypoglycemia
• Pentamidine: Can initially cause hypoglycemia followed by hyperglycemia, complicating insulin dosing

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Dosage

Insulin glargine dosing is highly individualized based on patient factors, blood glucose levels, and treatment goals. For adults with type 1 diabetes, typical starting doses range from 0.2 to 0.4 units per kilogram of body weight daily, representing roughly one-third to one-half of total daily insulin requirements. Type 2 diabetes patients typically begin with 10 units daily or 0.2 units per kilogram body weight, with gradual increases of 2-4 units every 3-7 days based on fasting glucose levels. The medication is administered once daily at the same time, preferably in the evening. All insulin dosing must be determined and adjusted by a healthcare provider based on regular blood glucose monitoring, lifestyle factors, and individual response to treatment.

Sources: FDA DailyMed drug labels (public domain), BNF, WHO Essential Medicines List. This article is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider before starting or stopping any medication.

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