Insulin Glargine

Reviewed on 3/17/2022

What Is Insulin Glargine and How Does It Work?

Insulin Glargine is a prescription medication used to treat type 1 and type 2 diabetes mellitus.

What Are Dosages of Insulin Glargine?

Adult and pediatric dosage

Injectable solution

  • 100 units/mL
  • Lantus (10mL vial)
  • Semglee (10mL vial)

Prefilled pen

  • 100 units/mL
  • Lantus SoloSTAR (3mL)
  • Basaglar KwikPen (3mL)
  • Semglee (3mL)
  • 300 units/mL
  • Toujeo SoloStar (1.5mL)
  • Toujeo Max SoloStar (3mL)

Interchangeable biosimilar

  • Semglee is the first biosimilar that is interchangeable with the reference product Lantus

Type 1 Diabetes Mellitus

Adult dosage

Initial dose

For insulin-naïve patients:

  • Start 1/3 of total daily insulin dose; use remaining 2/3 of daily insulin dose on short-acting, premeal insulin
  • Usual initial dose range: 0.2-0.4 units/kg; optimal glucose lowering effect may take 5 days to fully manifest and the first insulin glargine dose may be insufficient to cover metabolic needs in the first 24 hours of use 

Pediatric dosage

  • Toujeo is not approved for use in children. 
  • Children younger than 6 years of age: Safety and efficacy not established
  • Children 6 years of age or older: Start `1/3 of total daily insulin dose; use remaining 2/3 of daily insulin dose on short-acting, premeal insulin; usual daily maintenance range in adolescents is less than 1.2 units/kg/day during growth spurts

Type 2 Diabetes Mellitus

Adult dosage

Initial dose

  • For insulin-naïve patients
  • Start 0.2 units/kg once daily; if necessary, adjust the dosage of other antidiabetic drugs when starting insulin glargine to minimize the risk of hypoglycemia 

Dosage Considerations – Should be Given as Follows: 

  • See "Dosages."

What Are Side Effects Associated with Using Insulin Glargine?

Common side effects of Insulin Glargine include:

  • low blood sugar, 
  • itching, 
  • mild skin rash, and
  • thickening or hollowing of the skin where the injection was given

Serious side effects of Insulin Glargine include:

  • redness or swelling at the injection site, 
  • itchy skin rash over the entire body, 
  • trouble breathing, 
  • fast heartbeats, 
  • lightheadedness
  • swelling of the tongue or throat, 
  • rapid weight gain, 
  • swelling in the feet or ankles, 
  • leg cramps, 
  • constipation, 
  • irregular heartbeats, 
  • fluttering in the chest, 
  • increased thirst or urination, 
  • numbness or tingling, 
  • muscle weakness, and
  • limp feeling

Rare side effects of Insulin Glargine include:

  • none 
This is not a complete list of side effects and other serious side effects or health problems may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact With Insulin Glargine?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Insulin Glargine has severe interactions with the following drug:
    • pramlintide
  • Insulin Glargine has serious interactions with the following drugs:
  • Insulin Glargine has moderate interactions with at least 127 other drugs.
  • Insulin Glargine has minor interactions with at least 76 other drugs. 

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this drug, tell your doctor or pharmacist of all the drugs you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

What Are Warning And Precautions for Insulin Glargine?


  • Documented hypersensitivity.
  • During episodes of hypoglycemia.

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Insulin Glargine?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Insulin Glargine?”


  • Toujeo and Lantus are not interchangeable
  • Not recommended for treating diabetic ketoacidosis; use IV short-acting insulin instead
  • Never share insulin pens between patients, even if the needle is changed; pen sharing poses a risk for transmission of blood-borne pathogens
  • To avoid dosing errors and potential overdose, never use a syringe to remove the drug from TOUJEO SoloStar or TOUJEO Max SoloStar prefilled pen into a syringe
  • Decreased insulin requirements: Diarrhea, nausea/vomiting, malabsorption, hypothyroidism, renal impairment, hepatic impairment
  • Increased insulin requirements include fever, hyperthyroidism, trauma, infection, surgery
  • Increase frequency of glucose monitoring with changes to insulin dosage, co-administered glucose-lowering medications, meal pattern, or physical activity; and in patients with renal or hepatic impairment and hypoglycemia unawareness
  • Accidental mix-ups between insulin products can occur; instruct patients to check insulin labels before injection
  • Rapid changes in serum glucose may induce symptoms of hypoglycemia
  • Hypoglycemia is the most common cause of adverse reactions (eg, headache, tachycardia)
  • May cause a shift in potassium from extracellular to intracellular space, possibly leading to hypokalemia; caution when coadministered with potassium-lowering drugs or conditions that may decrease potassium
  • Frequent glucose monitoring and insulin dose reduction may be required with renal or hepatic impairment; not recommended during periods of rapidly declining renal or hepatic function because of risk for prolonged hypoglycemia
  • Use caution during pregnancy
  • Hyperglycemia or hypoglycemia with changes in insulin regimen
    • Changes in insulin, insulin strength, manufacturer, type, or method of administration may affect glycemic control and predispose to hypoglycemia or hyperglycemia
    • Changes should be made cautiously and only under close medical supervision and the frequency of blood glucose monitoring should be increased
    • Repeated insulin injections into areas of lipodystrophy or localized cutaneous amyloidosis reported to result in hyperglycemia; a sudden change in the injection site (to the unaffected area) has been reported to result in hypoglycemia
    • Make any changes to a patient’s insulin regimen under close medical supervision with increased frequency of blood glucose monitoring
    • Advise patients who have repeatedly injected into areas of lipodystrophy or localized cutaneous amyloidosis to change injection site to unaffected areas and closely monitor for hypoglycemia
    • For patients with type 2 diabetes, dosage adjustments in concomitant oral antidiabetic treatment may be needed
  • Cancer risk data inconclusive
    • The FDA reviewed 4 published observational studies, 3 of which suggested an increased risk of cancer associated with insulin glargine
    • It was determined that the evidence presented in these studies is inconclusive due to methodologic limitations
    • The duration of patient follow-up in all 4 studies was shorter than that which is generally considered necessary to evaluate cancer risk from drug exposure
    • Also, the 4 studies provided limited information on patients' use of insulin products; some studies did not take into account whether the patients used any antidiabetic drugs before the study period or whether there were any changes in how patients used these drugs during the study period
    • Furthermore, risk factors for cancer (eg, smoking, family history of cancer, obesity) may not have been adequately controlled for in these studies
  • Drug interactions overview
    • Thiazolidinediones are peroxisome proliferator-activated receptor (PPAR)-gamma agonists and can cause dose-related fluid retention, particularly when used in combination with insulin; fluid retention may lead to or exacerbate heart failure; monitor for signs and symptoms of heart failure, treat accordingly, and consider discontinuing thiazolidinediones
    • Coadministration with these drugs (eg, antidiabetic agents, ACE inhibitors, angiotensin II receptor blocking agents, disopyramide, fibrates, fluoxetine, monoamine oxidase inhibitors, pentoxifylline, pramlintide, propoxyphene, salicylates, somatostatin analogs [eg, octreotide], sulfonamide antibiotics, GLP-1 receptor agonists, DPP-4 inhibitors, and SGLT-2 inhibitors) may increase the risk of hypoglycemia
    • Coadministration with these drugs (eg, atypical antipsychotics [eg, olanzapine and clozapine], corticosteroids, danazol, diuretics, estrogens, glucagon, isoniazid, niacin, oral contraceptives, phenothiazines, progestogens [eg, oral contraceptives], protease inhibitors, somatropin, sympathomimetic agents [eg, albuterol, epinephrine, terbutaline], and thyroid hormones) may decrease the risk of hypoglycemia
    • Concomitant use of alcohol, beta-blockers, clonidine, and lithium salts with insulin glargine may increase or decrease the blood-glucose-lowering effect of insulin glargine
    • Pentamidine may cause hypoglycemia, which may sometimes be followed by hyperglycemia
    • Coadministration with beta-blockers, clonidine, guanethidine, or reserpine may blunt signs and symptoms of hypoglycemia

Pregnancy and Lactation

  • Published data do not report a clear association with insulin glargine products and major birth defects, miscarriage, or adverse maternal or fetal outcomes when insulin glargine products are used during pregnancy; however, these studies cannot establish the absence of any risk because of methodological limitations including small sample size and some with no comparative group
  • There are risks to mother and fetus associated with poorly controlled diabetes in pregnancy; poorly controlled diabetes in pregnancy increases the maternal risk for diabetic ketoacidosis, pre-eclampsia, spontaneous abortions, preterm delivery, stillbirth, and delivery complications
  • There are no data on the presence of insulin glargine in human milk, effects on the breastfed infant, or milk production
  • The use of insulin glargine is compatible with breastfeeding, but women with diabetes who are lactating may require adjustments of their insulin doses; health benefits of breastfeeding should be considered along with the mother’s clinical need for therapy and any potential adverse effects on the breastfed child from the drug or underlying maternal condition. 
Medscape. Insulin Glargine.

Health Solutions From Our Sponsors