05 Endocrine and Diabetes Medications

Insulin therapy

Insulin replaces or supplements pancreatic insulin. People with type 1 diabetes require it. In type 2 diabetes, it may be added when other treatment does not adequately control blood glucose or in certain clinical situations.

Insulin is commonly grouped by how quickly it works and whether it provides meal-time coverage, called bolus or prandial coverage, or background coverage, called basal coverage. All insulin can cause hypoglycemia. Some products are available in different concentrations, so the exact product matters. Timing varies by product and formulation; a class label is not a dosing instruction.

• Rapid-acting: insulin lispro (Humalog), insulin aspart (NovoLog), and insulin glulisine (Apidra) work quickly and provide meal-time or bolus coverage.

• Short-acting: regular human insulin (Humulin R, Novolin R) is used for meal-time coverage and is the classic insulin used intravenously in some acute-care settings.

• Intermediate-acting: insulin NPH, also called isophane (Humulin N, Novolin N), provides intermediate basal coverage and has a noticeable peak.

• Long-acting basal: insulin glargine (Lantus, Basaglar, Toujeo) provides background coverage and generally has little or no pronounced peak.

• Ultra-long-acting basal: insulin degludec (Tresiba) provides extended background coverage.

• Inhaled rapid-acting: human insulin delivered by inhalation (Afrezza) provides meal-time coverage; it is not a substitute for basal insulin when basal coverage is needed.

A useful timing association is lispro, aspart, and glulisine as rapid-acting; regular as short-acting; NPH as intermediate-acting; and glargine and degludec as basal insulins.

Glucose-lowering medicines

Oral and other glucose-lowering medicines primarily treat type 2 diabetes; they do not replace insulin in type 1 diabetes. The classes act in different ways, and some of their risks or benefits depend on a patient's other conditions. Brand examples are familiar U.S. examples; availability and marketed brands can change, and combination products may contain more than one generic drug.

Medicines that affect insulin release or sensitivity

• Biguanide: metformin (Glucophage) lowers liver glucose production and improves insulin sensitivity. Gastrointestinal effects are common; metformin usually does not cause hypoglycemia by itself.

• Sulfonylureas: glipizide (Glucotrol), glimepiride (Amaryl), and glyburide (DiaBeta) stimulate pancreatic insulin release. They can cause hypoglycemia and weight gain.

• Meglitinides: repaglinide (Prandin) and nateglinide (Starlix) stimulate insulin release for a short time around meals. Hypoglycemia is possible.

• Thiazolidinedione (TZD): pioglitazone (Actos) improves insulin sensitivity. It can cause fluid retention and worsen heart failure.

Medicines that act through incretins or the intestine

• DPP-4 inhibitors: sitagliptin (Januvia), linagliptin (Tradjenta), and saxagliptin (Onglyza) increase incretin hormone activity, supporting glucose-dependent insulin release. This class is often tested as generally weight-neutral.

• GLP-1 receptor agonists: oral semaglutide (Rybelsus) increases glucose-dependent insulin release and slows gastric emptying; nausea and other gastrointestinal effects may occur. Injectable examples include dulaglutide (Trulicity), liraglutide (Victoza), and exenatide (Byetta, Bydureon). This class is not insulin.

• Alpha-glucosidase inhibitor: acarbose (Precose) slows carbohydrate digestion and absorption in the intestine and can cause gastrointestinal effects.

Medicines that promote urinary glucose loss

• SGLT2 inhibitors: empagliflozin (Jardiance), dapagliflozin (Farxiga), and canagliflozin (Invokana) promote urinary glucose excretion. Testable risks include genital yeast infections and, rarely, ketoacidosis.

Pramlintide (Symlin) is an injectable amylin analogue used with mealtime insulin in selected patients; it is not a substitute for insulin. The main class contrasts are that metformin decreases hepatic glucose output, sulfonylureas increase insulin secretion and can cause hypoglycemia, SGLT2 inhibitors increase glucose loss in urine, and GLP-1 medicines act through incretin pathways.

Thyroid medications

Thyroid medicines may replace hormone or reduce its production, depending on whether thyroid hormone is low or excessive.

• Levothyroxine (Synthroid, Levoxyl, Tirosint) is synthetic T4 and the first-line replacement for hypothyroidism. It is a replacement hormone, not an antithyroid drug. Calcium and iron can interfere with its absorption, so they are commonly separated from it.

• Liothyronine (Cytomel) is synthetic T3 used for thyroid-hormone replacement; it is used less commonly than levothyroxine.

• Methimazole (Tapazole) is a thionamide antithyroid drug that reduces thyroid-hormone production. It is commonly used for hyperthyroidism, including Graves disease. Fever or sore throat while taking methimazole warrants prompt clinical evaluation because of the risk of low white blood cell counts.

• Propylthiouracil (PTU) is a thionamide antithyroid drug. It reduces thyroid-hormone production and also reduces peripheral T4-to-T3 conversion. It is often preferred over methimazole during the first trimester of pregnancy; serious liver injury is an important risk.

The central distinction is that levothyroxine treats low thyroid hormone, while methimazole and PTU treat excess thyroid hormone.

Corticosteroids and adrenal replacement

Corticosteroids include glucocorticoids, which have anti-inflammatory and immunosuppressive effects, and drugs with mineralocorticoid activity, which affects salt and fluid balance. Common systemic glucocorticoids include prednisone (Deltasone), prednisolone (Orapred), methylprednisolone (Medrol), dexamethasone (Decadron), and hydrocortisone (Cortef). They are used for many inflammatory and immune conditions; hydrocortisone also replaces cortisol in adrenal insufficiency.

Long-term or high-dose systemic corticosteroid use can suppress the body's own cortisol production and may raise blood glucose. Prolonged therapy should not be stopped abruptly without medical direction; a gradual dose reduction may be required.

For primary adrenal insufficiency, hydrocortisone commonly replaces cortisol, while fludrocortisone (Florinef) replaces aldosterone when needed. Stress or illness may require clinician-directed adjustment of replacement therapy.

Other endocrine therapies

Several other endocrine medicines are associated with specific hormone-related conditions or emergencies.

• Desmopressin (DDAVP) is a vasopressin analogue, or antidiuretic hormone, used for central diabetes insipidus. It reduces excessive urine production; monitor for water retention and low sodium. It treats central diabetes insipidus by acting like antidiuretic hormone, and diabetes insipidus is distinct from diabetes mellitus.

• Cabergoline (Dostinex) and bromocriptine (Parlodel) are dopamine agonists used for hyperprolactinemia, often from a prolactin-secreting pituitary tumor. They reduce prolactin secretion; bromocriptine also has other uses.

• Octreotide (Sandostatin) is a somatostatin analogue used for acromegaly and for symptoms from certain hormone-secreting tumors. In appropriate cases, it suppresses growth-hormone secretion.

• Glucagon (Gvoke, Baqsimi, Zegalogue) is a hyperglycemic hormone used for emergency treatment of severe hypoglycemia when a person cannot safely take oral glucose.

• sulfonylurea

• SGLT2 inhibitor

• GLP-1 receptor agonist