Chart — Endocrine
Diabetes Medication Classes Chart
Biguanides, sulfonylureas, GLP-1 agonists, SGLT2 inhibitors, DPP-4 inhibitors, meglitinides, TZDs, and insulin — mechanisms, hypoglycemia risk, key side effects, and nursing considerations.
Educational use only. Antidiabetic therapy is individualized based on A1C, renal/hepatic function, cardiovascular history, weight, and patient preference. Always follow provider orders and institutional protocols. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Biguanides
Examples: Metformin (Glucophage)
| Mechanism | Reduces hepatic glucose production (gluconeogenesis); improves insulin sensitivity in peripheral tissues; does NOT stimulate insulin secretion |
| Hypoglycemia Risk | None (monotherapy) — does not stimulate insulin secretion |
| Side Effects | GI: nausea, diarrhea, abdominal cramping (take with food); metallic taste; vitamin B12 deficiency with long-term use |
| Contraindications | eGFR < 30 (risk of lactic acidosis with renal accumulation); hold before IV contrast and major surgery; active alcoholism; heart failure (historically — now reconsidered by ADA) |
| Nursing Considerations | First-line agent for Type 2 DM. Hold 24–48h before contrast procedures; restart after confirming renal function. Check annual B12 with long-term use. Take with meals to reduce GI upset. Monitor eGFR. |
| NCLEX Focus | Metformin does NOT cause hypoglycemia alone. HOLD before IV contrast. Lactic acidosis (rare but serious) — signs: weakness, cramping, respiratory distress. First-line Type 2 DM. |
Sulfonylureas
Examples: Glipizide (Glucotrol), Glyburide (DiaBeta), Glimepiride (Amaryl)
| Mechanism | Stimulates pancreatic beta cells to release insulin — insulin release is glucose-INDEPENDENT (release occurs even at normal/low glucose levels) |
| Hypoglycemia Risk | HIGH — stimulates insulin release independent of blood glucose level |
| Side Effects | Hypoglycemia (especially with missed meals, renal failure, alcohol), weight gain |
| Contraindications | Renal failure (accumulation → prolonged hypoglycemia); hepatic failure; Type 1 DM (no functional beta cells); sulfa allergy (cross-reactivity — less clear with newer agents) |
| Nursing Considerations | Highest oral hypoglycemia risk. Glipizide preferred in elderly/renal impairment (shorter acting). Glyburide contraindicated in renal failure. Ensure patient eats before giving. Prolonged hypoglycemia with overdose — needs hospital monitoring. |
| NCLEX Focus | Sulfonylureas CAUSE HYPOGLYCEMIA — always take with meals. Glyburide contraindicated in elderly and renal failure (long-acting, metabolite accumulation). Mechanism: stimulates insulin secretion. |
GLP-1 Receptor Agonists
Examples: Semaglutide (Ozempic/Wegovy/Rybelsus), Liraglutide (Victoza), Dulaglutide (Trulicity), Exenatide (Byetta)
| Mechanism | Mimics GLP-1 (incretin hormone) → glucose-DEPENDENT insulin secretion, suppresses glucagon, slows gastric emptying, promotes satiety |
| Hypoglycemia Risk | Low (monotherapy) — glucose-dependent insulin release (only works when glucose is elevated) |
| Side Effects | Nausea, vomiting, diarrhea (usually transient — improves in 4–8 weeks); pancreatitis risk (stop if pancreatitis symptoms); injection site reactions (SQ); weight loss (beneficial in T2DM) |
| Contraindications | Personal or family history of medullary thyroid cancer or MEN 2 (Black Box Warning — thyroid C-cell tumors in animal studies); pancreatitis history |
| Nursing Considerations | Cardiovascular benefits (liraglutide, semaglutide) — preferred in DM with established CVD. Weight loss benefit. Teach proper SQ injection technique and rotation. Refrigerate unopened pens; room temp once in use. Nausea common early — start low dose. |
| NCLEX Focus | Black Box Warning: thyroid C-cell tumor risk (MEN 2, medullary thyroid CA = contraindication). Nausea expected initially. Weight loss beneficial. CV protection demonstrated. |
SGLT2 Inhibitors
Examples: Empagliflozin (Jardiance), Dapagliflozin (Farxiga), Canagliflozin (Invokana)
| Mechanism | Blocks SGLT2 in proximal renal tubule → prevents glucose reabsorption → glucosuria (glucose spilled into urine). Also: natriuresis, blood pressure reduction, weight loss. |
| Hypoglycemia Risk | Low (monotherapy) — glucose-independent mechanism |
| Side Effects | UTI and genital mycotic infections (increased glucose in urine is culture medium); polyuria; volume depletion/hypotension; DKA (even with normal/near-normal glucose — euglycemic DKA); Fournier's gangrene (rare, serious); lower limb amputation risk (canagliflozin) |
| Contraindications | eGFR < 30 (no efficacy); Type 1 DM (euglycemic DKA risk); recurrent UTI or genital infections |
| Nursing Considerations | Benefits: cardiovascular (empagliflozin, dapagliflozin) and renal protection. HOLD before major surgery and procedures (euglycemic DKA risk). Teach genital hygiene and UTI recognition. Educate about euglycemic DKA — can occur with normal glucose. |
| NCLEX Focus | SGLT2 inhibitors cause UTIs and genital fungal infections (glucose in urine). EUGLYCEMIC DKA — DKA can occur with normal glucose (unusual for DKA). Hold before surgery. Fournier's gangrene: report perineal pain/swelling immediately. |
DPP-4 Inhibitors (Gliptins)
Examples: Sitagliptin (Januvia), Saxagliptin (Onglyza), Linagliptin (Tradjenta), Alogliptin (Nesina)
| Mechanism | Inhibits DPP-4 enzyme → prevents breakdown of endogenous GLP-1 and GIP → prolongs incretin activity → glucose-dependent insulin secretion and glucagon suppression |
| Hypoglycemia Risk | Low — glucose-dependent mechanism |
| Side Effects | Generally well-tolerated; nasopharyngitis, headache; pancreatitis (rare); joint pain (arthralgia); saxagliptin associated with increased HF hospitalization |
| Contraindications | Saxagliptin: caution in heart failure; renal dose adjustment required for most agents (except linagliptin — hepatic elimination) |
| Nursing Considerations | Weight-neutral (advantage over sulfonylureas). Linagliptin preferred if renal impairment (no renal dosing). Well-tolerated and low hypoglycemia risk. Less potent glucose-lowering than GLP-1 agonists. |
| NCLEX Focus | DPP-4 inhibitors = weight NEUTRAL (vs GLP-1 = weight loss). Low hypoglycemia risk. Pancreatitis risk — monitor for abdominal pain. Linagliptin is the only DPP-4 inhibitor without renal dose adjustment. |
Meglitinides (Glinides)
Examples: Repaglinide (Prandin), Nateglinide (Starlix)
| Mechanism | Stimulates pancreatic beta cell insulin release — similar to sulfonylureas but shorter duration; taken before each meal |
| Hypoglycemia Risk | MODERATE — stimulates insulin release (but shorter-acting, lower risk than sulfonylureas if meal is eaten) |
| Side Effects | Hypoglycemia (if meal delayed or skipped); weight gain; less risk than sulfonylureas for prolonged hypoglycemia |
| Contraindications | Type 1 DM; skip dose if skipping meal (key teaching point) |
| Nursing Considerations | Take with each meal — if meal is skipped, SKIP the dose. More flexible dosing schedule than sulfonylureas (variable meal schedule). Used when meal times are irregular. |
| NCLEX Focus | Take RIGHT BEFORE each meal. If no meal → skip dose. SHORT-acting — flexible meal schedules. Same mechanism as sulfonylureas but shorter-acting. |
Thiazolidinediones (TZDs)
Examples: Pioglitazone (Actos), Rosiglitazone (Avandia)
| Mechanism | PPAR-gamma agonist → increases insulin sensitivity in adipose, muscle, and liver tissue; does NOT stimulate insulin secretion |
| Hypoglycemia Risk | Low (monotherapy) — improves insulin sensitivity, does not stimulate secretion |
| Side Effects | Fluid retention / edema; weight gain; increased fracture risk (especially in women — bone density changes); heart failure worsening; bladder cancer risk with pioglitazone (long-term); slow onset (weeks for full effect) |
| Contraindications | Heart failure (NYHA Class III-IV) — worsens fluid retention; bladder cancer history (pioglitazone); liver disease; use during pregnancy |
| Nursing Considerations | Monitor for fluid retention, edema, weight gain, and heart failure signs (dyspnea, dependent edema). Rosiglitazone: restricted use due to CV concerns. Avoid in patients with CHF. Slow onset — weeks to see full effect. |
| NCLEX Focus | TZDs cause FLUID RETENTION → worsen heart failure (avoid in CHF). Weight gain and bone fracture risk. Slow onset of action. Do NOT use in NYHA Class III-IV heart failure. |
Insulin
Examples: Rapid: Lispro (Humalog), Aspart (NovoLog); Short: Regular (Humulin R); Intermediate: NPH; Long: Glargine (Lantus), Detemir (Levemir), Degludec (Tresiba)
| Mechanism | Replaces/supplements endogenous insulin; binds insulin receptors → glucose uptake in cells, suppresses hepatic glucose production, promotes glycogen/fat/protein synthesis |
| Hypoglycemia Risk | HIGH — stimulates glucose uptake at any glucose level |
| Side Effects | Hypoglycemia, weight gain, lipodystrophy at injection sites, local reactions |
| Contraindications | Relative: hypoglycemia (obvious) — adjust dose, not hold |
| Nursing Considerations | Site rotation to prevent lipodystrophy. Do NOT mix glargine or detemir with other insulins. Regular insulin is the ONLY insulin given IV. Check glucose before administration. Basal-bolus-correctional (BBC) preferred over sliding scale alone. SQ transition from drip: overlap 2–4 hours. |
| NCLEX Focus | ONLY Regular insulin given IV/IV drip. Rotate injection sites — check for lipodystrophy. Do NOT mix long-acting (glargine) with short-acting in syringe. NPH can be mixed with Regular. Cloudy insulins: NPH (normal) vs others (abnormal — discard). |
Quick Hypoglycemia Risk Summary
HIGH Risk
Sulfonylureas, Insulin
MODERATE Risk
Meglitinides (if meal skipped)
LOW Risk
Metformin, GLP-1, SGLT2, DPP-4, TZDs
Related Resources
Hospital Glycemic Management GuideInpatient insulin protocols, basal-bolus, NPO management, insulin drip
Open →Hypoglycemia Management GuideRule of 15, D50W, glucagon, and severity classification
Open →Diabetes Patient Education ReferenceSick-day rules, insulin storage, glucose monitoring, foot care
Open →Standards & sources
Fact-checked Jun 20, 2026This page is written to align with American Diabetes Association (ADA) Standards of Care · American Association of Clinical Endocrinology (AACE). It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →