Action

Long-acting insulin form. Promotes glucose transport, which stimulates carbohydrate metabolism in skeletal and cardiac muscle and adipose tissue. Also promotes phosphorylation of glucose in liver, where it's converted to glycogen. Directly affects fat and protein metabolism, stimulates protein synthesis, inhibits release of free fatty acids, and indirectly decreases phosphate and potassium.

Availability

Injection: 100 units/ml in 10-ml vials and 3-ml cartridges

Indications and dosages

➣ Type 1 (insulin-dependent) diabetes mellitus and type 2 (non-insulin-dependent) diabetes mellitus in patients who need long-acting insulin

Adults and children ages 6 and older: Subcutaneous injection daily at same time each day, with dosage based on blood glucose level

➣ Conversion from another insulin type in patients with type 1 diabetes mellitus who need long-acting insulin

Adults and children ages 6 and older: For patients switching from once-daily NPH or ultralente human insulin, start glargine at same dosage as current insulin dosage. For patients taking twice-daily NPH or ultralente human insulin, reduce initial glargine dosage by approximately 20% of current insulin dosage during week 1; then adjust based on blood glucose level.

➣ Type 2 diabetes mellitus in patients receiving oral hypoglycemics

Adults: Dosage highly individualized based on glucose levels and response

Contraindications

• Hypersensitivity to drug or its components

• Hypoglycemia

Precautions

Use cautiously in:

• pregnant or breastfeeding patients

• children.

Administration

See Be aware that insulin is a high-alert drug.

• Give by subcutaneous route only, at same time each day.

See Don't mix in solution with other drugs, including other insulins.

• Before drawing up insulin into syringe, roll vial between hands to ensure uniform dispersion; don't shake.

• Rotate injection sites to prevent lipodystrophy.

Adverse reactions

Metabolic: rebound hyperglycemia (Somogyi effect), hypoglycemia

Skin: urticaria, rash, pruritus, redness, stinging, or warmth at injection site

Other: edema, lipodystrophy, lipohypertrophy, allergic reactions including anaphylaxis

Interactions

Drug-drug. Acetazolamide, albuterol, antiretrovirals, asparaginase, calcitonin, corticosteroids, cyclophosphamide, danazol, dextrothyroxine, diazoxide, diltiazem, diuretics, dobutamine, epinephrine, estrogens, hormonal contraceptives, isoniazid, morphine, niacin, phenothiazines, phenytoin, somatropin, terbutaline, thyroid hormones: decreased hypoglycemic effect

Anabolic steroids, angiotensin-converting enzyme inhibitors, calcium, chloroquine, clofibrate, clonidine, disopyramide, fluoxetine, guanethidine, mebendazole, MAO inhibitors, octreotide, oral hypoglycemics, phenylbutazone, propoxyphene, pyridoxine, salicylates, sulfinpyrazone, sulfonamides, tetracyclines: increased hypoglycemic effect

Beta-adrenergic blockers (nonselective): masking of some hypoglycemia signs and symptoms, delayed recovery from hypoglycemia

Lithium carbonate: altered hypoglycemic effect

Pentamidine: increased hypoglycemic effect, possibly followed by hyperglycemia

Drug-diagnostic tests. Glucose, inorganic phosphate, magnesium, potassium: decreased levels

Liver and thyroid function studies: test interference

Urine vanillylmandelic acid: increased level

Drug-herbs. Basil, bee pollen, burdock, glucosamine, sage: altered glycemic control

Chromium, coenzyme Q10, dandelion, eucalyptus, fenugreek, marshmallow: increased hypoglycemic effect

Garlic, ginseng: decreased blood glucose level

Drug-behaviors. Alcohol use: increased hypoglycemic effect

Marijuana use: increased blood glucose level

Smoking: increased blood glucose level, decreased response to insulin

Patient monitoring

• Monitor blood glucose level frequently to assess drug efficacy and appropriateness of dosage.

• Watch blood glucose level closely if patient is converting from one insulin type to another or is under unusual stress (as from surgery or trauma).

See Check for signs and symptoms of hypoglycemia (such as CNS changes). Keep glucose source at hand.

See Monitor for signs and symptoms of hyperglycemia, such as polydipsia, polyphagia, polyuria, and diabetic ketoacidosis (blood and urine ketones, metabolic acidosis, extremely elevated glucose level, hypovolemia).

• Monitor for glycosuria.

• Closely monitor kidney and liver function test results in patients with renal or hepatic impairment.

Patient teaching

• Instruct patient how to administer insulin subcutaneously.

See Teach patient how to recognize and report signs and symptoms of hypoglycemia and hyperglycemia. Advise him to always carry glucose source.

• Advise patient to rotate subcutaneous injection sites and keep a record of sites used.

• Teach patient how to monitor and record blood glucose level and, if indicated, urine glucose and ketone levels.

• Inform patient that changes in diet, activity, and stress level can affect blood glucose level and insulin requirements.

• Advise patient to wear medical identification stating that he is diabetic and takes insulin.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, herbs, and behaviors mentioned above.