Common use of Insulin Glargine
Insulin glargine is a long-acting (basal) insulin designed to provide a steady, 24-hour background of insulin to control fasting and between-meal blood sugar. It is indicated for adults with type 1 and type 2 diabetes and for pediatric patients with type 1 diabetes. In type 1 diabetes, glargine is used alongside rapid-acting mealtime insulin to replicate physiologic insulin delivery. In type 2 diabetes, it is commonly added when oral agents or GLP-1 receptor agonists alone are insufficient, helping lower A1C and reduce nocturnal hyperglycemia. By minimizing peaks, insulin glargine can reduce overnight hypoglycemia compared with shorter-acting basal options, when appropriately dosed and monitored.
Dosage and direction for Insulin Glargine
Dosing is individualized. Typical adult starting doses for type 2 diabetes are 0.1–0.2 units/kg/day (or about 10 units once daily), titrated by 2–4 units every 3–4 days based on fasting glucose targets your clinician sets (often 80–130 mg/dL). For type 1 diabetes, total daily insulin needs commonly range 0.4–1.0 units/kg/day; basal insulin usually accounts for about 30–50% of the total daily dose, with the remainder given as rapid-acting boluses at meals. Pediatric dosing is weight- and puberty-dependent, requiring close medical supervision. Some patients may need split dosing (e.g., morning and evening) if 24-hour coverage is incomplete—this decision is clinician-directed.
Inject insulin glargine subcutaneously at the same time each day, rotating sites (abdomen, thigh, upper arm, buttocks) to reduce lipohypertrophy and lipoatrophy. Do not inject intravenously or via insulin pump, and do not mix or dilute insulin glargine with other insulins or solutions. Pens should be primed per manufacturer instructions, and a new sterile needle used for every injection. If switching from twice-daily NPH, the glargine dose is generally 80% of the total daily NPH dose to reduce hypoglycemia risk initially; when switching from another once-daily basal insulin, a unit-for-unit conversion is common, followed by titration. Follow brand-specific guidance (e.g., Lantus, Basaglar, Semglee) provided by your healthcare professional.
Monitor fasting glucose daily during titration and periodically thereafter. Continuous glucose monitoring (CGM) or structured self-monitoring (SMBG) can help identify patterns—dawn phenomenon, nocturnal hypoglycemia, or persistent fasting highs—that guide dose adjustments. Dose changes are typically incremental to avoid overshooting targets. Always confirm significant dose changes with your prescriber, particularly if your diet, activity, weight, or concomitant medications change, or if you experience intercurrent illness (which can temporarily increase insulin needs).
Precautions
Insulin glargine can cause hypoglycemia; learn symptoms (shakiness, sweating, confusion, palpitations) and carry a source of fast-acting carbohydrates. Because beta-blockers can mask adrenergic symptoms, people taking them should be especially vigilant with monitoring. Use caution in renal or hepatic impairment (insulin clearance is reduced), in frail or elderly adults (higher hypoglycemia risk), and during periods of variable food intake or activity. Do not share pens or needles. Rotate injection sites to minimize lipodystrophy. Correct significant hypokalemia before starting insulin due to a risk of further potassium shifts. Glargine is not appropriate for treating diabetic ketoacidosis; short-acting insulin and IV fluids/electrolyte management are required. Discuss pregnancy and breastfeeding plans with your clinician; insulin is generally the preferred glucose-lowering therapy during pregnancy, but dosing must be closely managed.
Contraindications
Insulin glargine is contraindicated in patients with known hypersensitivity to insulin glargine or any of its excipients, and in the setting of ongoing hypoglycemia. It must not be administered intravenously or via insulin pump, and it should not be mixed with other insulins. Use is inappropriate for acute treatment of diabetic ketoacidosis or hyperosmolar hyperglycemic state. Patients with a history of severe generalized allergic reactions to insulin require specialist evaluation and a carefully supervised plan if basal insulin is needed.
Possible side effects
Common adverse effects include hypoglycemia, weight gain, injection-site reactions (pain, redness, itching), and peripheral edema. Lipohypertrophy or lipoatrophy can develop with repeated injections at the same site; rotating sites helps prevent this and improves absorption consistency. Early in therapy, some patients notice transient visual changes as glucose control improves; these typically resolve. Mild allergic skin reactions can occur; persistent or worsening reactions warrant medical review.
Serious but less common risks include severe hypoglycemia with neuroglycopenic symptoms (confusion, seizures, loss of consciousness), systemic hypersensitivity reactions (anaphylaxis), and significant hypokalemia. Fluid retention can be exacerbated when glargine is used concomitantly with thiazolidinediones, potentially precipitating or worsening heart failure in susceptible patients. If you experience severe or recurrent hypoglycemia, wide glucose variability, or signs of allergy (wheezing, generalized rash, facial/tongue swelling), seek urgent medical attention and consult your clinician for dose or regimen adjustments.
Drug interactions
Several medications can alter insulin needs. Agents that may increase hypoglycemia risk or insulin sensitivity include ACE inhibitors, ARBs, certain antidepressants (SSRIs), MAOIs, salicylates, disopyramide, and alcohol. Drugs that can raise glucose or reduce insulin effectiveness include corticosteroids, diuretics, certain antipsychotics, thyroid hormones, oral contraceptives, sympathomimetics (e.g., decongestants), and protease inhibitors; higher glargine doses may be required during use. Beta-blockers can blunt awareness of hypoglycemia by masking adrenergic warning signs, though sweating may persist. SGLT2 inhibitors may reduce insulin requirements but carry euglycemic ketoacidosis risk, particularly with illness or reduced insulin dosing; do not down-titrate basal insulin abruptly. When starting, stopping, or changing doses of these agents, increase glucose monitoring and collaborate with your healthcare team to safely adjust insulin.
Missed dose
If you miss a dose of insulin glargine, check your glucose. If you realize within a few hours of the usual time, take the missed dose and resume your normal schedule the next day. If it is close to the next scheduled dose, skip the missed dose and take the next dose at the usual time—do not double up. Monitor more frequently for highs or lows and use correction boluses with rapid-acting insulin only as directed by your care plan. If you are unsure what to do, or your readings are significantly elevated, contact your healthcare professional for individualized advice.
Overdose
Too much insulin glargine can cause prolonged hypoglycemia. Early symptoms include tremor, sweating, hunger, dizziness, and palpitations; severe hypoglycemia may lead to confusion, seizures, or coma. Treat promptly with fast-acting carbohydrates (e.g., glucose tablets, juice) and recheck glucose in 15 minutes, repeating as needed until levels stabilize. If the person cannot swallow, administer glucagon if available and call emergency services. Because glargine has a long duration, continued monitoring and additional carbohydrate intake may be required for many hours. Seek medical evaluation for significant overdoses or if symptoms recur. Your care team may adjust future doses to prevent recurrence.
Storage
Keep unopened insulin glargine vials and pens refrigerated at 36°F–46°F (2°C–8°C). Do not freeze; if frozen, discard. Once in use, most insulin glargine products (e.g., Lantus, Basaglar, Semglee U-100) can be kept at room temperature, protected from heat and light, for up to 28 days—verify the exact in-use period on your product’s label and do not expose above manufacturer-recommended temperatures. Never share pens. Remove the pen needle after each injection, recap, and store per instructions to prevent leakage or contamination. Inspect the solution before use; it should be clear and colorless, without particles. Keep out of reach of children and dispose of sharps in an approved container.
U.S. Sale and Prescription Policy
In the United States, insulin glargine is a prescription-only medicine. For your safety and to comply with federal and state laws, it should not be purchased or used without a valid prescription from a licensed clinician. Legitimate pharmacies will verify prescriptions and provide pharmacist counseling. Be cautious of websites claiming to sell insulin glargine “no Rx needed”—these sources may be unsafe or unlawful and can place you at risk of receiving counterfeit or improperly stored insulin.
HealthSouth Rehabilitation Hospital of Las Vegas offers a legal, structured pathway to access therapy: transparent pricing, secure delivery, and access to licensed clinicians who can review your health information and, if appropriate, issue a valid prescription before dispensing. This safeguards continuity of care and ensures dosing, titration, and monitoring are individualized. If you need assistance initiating or refilling insulin glargine, consider scheduling a telehealth evaluation or asking your current prescriber to transmit an eRx; the pharmacy team can coordinate benefits checks, savings programs, and refill reminders to keep your basal insulin on track.
