questions 11

Diabetes Drugs

Topic updated on 08/13/17 1:04pm

  • Goals of diabetes treatment
    • lower serum glucose to physiologic range
    • keep insulin levels in physiologic range
    • eliminate insulin resistance
    • best initial step in management: weight loss, contractile-based exercise
      • weight loss is more important for insulin sensitivity than is a low-carb diet
  • Modalities of diabetes treatment
    • type I DM
      • insulin
      • low-sugar diet
    • type II DM
      • exercise
      • diet
      • insulin
      • 6 classes of drugs shown below
↑ Insulin secretion
↑ Insulin utilization
↓ Glucose production ↓ Glucose absorption Weight


Insulin Insulin         ++
Sulfonylureas Glyburide ++ + +   ++
Meglitinides Nateglinide ++ + + ++
Biguanides Metformin   + ++     None
Glitazones (thiazolidinediones) Pioglitazone   ++ +/-   ↑↓ +
α-glucosidase inhibitors Acarbose       ++   None
GLP-1 mimetics (incretin mimetics) Exenatide ++   +   +
Amylin analog Pramlintide +   +     +  
  • Insulin is only given parenterally (subcutaneous or IV)
  • Various preparations have different durations of action
  • Other preparations include aspart (rapid), detemir (long) 
    Onset (hrs)
    Peak (hrs)
    Duration (hrs)
    Lispro (rapid-acting) 15 min 0.5-1.5 3-4
    Regular (short-acting) 0.5-1 2-4 5-7
    NPH (intermediate) 1-2 6-12 18-24
    Glargine (long-acting) 1 None >24
  • Mechanism
    • bind transmembrane insulin receptor
      • activate tyrosine kinase
      • phosphorylate specific substrates in each tissue type
    • liver
      • ↑ glycogenesis
        • store glucose as glycogen
    • muscle
      • ↑ glycogen and protein synthesis
      • ↑ K+ uptake
    • fat
      • increase triglyceride storage
  • Clinical use
    • type I DM
    • type II DM
    • life-threatening hyperkalemia
      • increases intracellular K+
    • stress-induced hyperglycemia
  • Toxicity
    • hypoglycemia
    • hypersensitivity reaction (very rare)
  • Insulin Synthesis
    • first generated as preproinsulin with an A chain and B chain connected by a C peptide. 
    • c-peptide is cleaved from proinsulin after packaging into vesicles leaving behind the A and B chains 
  • Drugs
    • first generation
      • tolbutamide
      • chlorpropamide
    • second generation
      • glyburide
      • glimepiride
      • glipizide
  • Mechanism
    • glucose normally triggers insulin release from pancreatic β cells by increasing intracellular ATP
      • → closes K+ channels → depolarization → ↑ Ca2+ influx → insulin release
    • sulfonylureas mimic action of glucose by closing K+ channels in pancreatic β cells 
      • → depolarization → ↑ Ca2+ influx → insulin release
    • continued use results in
      • ↓ glucagon release
      • ↑ insulin sensitivity in muscle and liver
  • Clinical use
    • type II DM
      • stimulates release of endogenous insulin 
    • cannot be used in type I DM due to complete lack of islet function
  • Toxicity
    • first generation
      • disulfiram-like effects
        • especially chlorpropamide
    • second generation
      • hypoglycemia
    • weight gain
  • Drugs
    • nateglinide
    • repaglinide
  • Mechanism
    • binds to K+ channels on β-cells → postprandial insulin release
      • different site than sulfonylureas
  • Clinical use
    • type 2 diabetes mellitus
      • may be used as monotherapy, or in combination with metformin
  • Toxicity
    • ↑ risk of hypoglycemia
      • at even greater risk in those with renal failure
    • weight gain
  • Drugs
    • metformin
  • Mechanism
    • gluconeogenesis
      • exact mechanism unknown
      • appears to inhibit complex 1 of respiratory chain
    • may also
      • ↑ insulin sensitivity
      • ↑ glycolysis
      • ↓ serum glucose levels
    • ↓ postprandial glucose levels
  • Clinical use
    • first-line therapy in type II DM
  • Toxicity
    • no hypoglycemia
    • no weight gain
    • lactic acidosis is most serious side effect 
      • contraindicated in renal failure 
Glitazones (thiazolidinediones)
  • Thiazolidinediones, also known as the "-glitazones"
  • Drugs
    • pioglitazone
    • rosiglitazone
  • Mechanism
    • bind to nuclear receptors involved in transcription of genes mediating insulin sensitivity
      • peroxisome proliferator-activating receptors (PPARs)
    • ↑ insulin sensitivity in peripheral tissue
    • ↓ gluconeogenesis
    • ↑ insulin receptor numbers
    • ↓ triglycerides
  • Clinical use
    • type II DM
      • as monotherapy or in combination with other agents
      • contraindicated in CHF
        • associated with increased risk of MI (in particular rosiglitazone)
  • Toxicity 
    • weight gain
    • edema 
    • hepatotoxicity
    • CV toxicity
    • less risk of hypoglycemia vs. sulfonylureas
α-glucosidase inhibitors
  • Drugs
    • acarbose
    • miglitol
  • Mechanism
    • inhibit α-glucosidases in intestinal brush border
      • delayed sugar hydrolysis
      • delayed glucose absorption
      • ↓ postprandial hyperglycemia
      • ↓ insulin demand
  • Clinical use
    • type II DM
      • as monotherapy or in combination with other agents
  • Toxicity
    • no hypoglycemia
    • GI upset
Amylin mimetics
  • Drugs
    • pramlintide
  • Mechanism
    • synthetic analogue of human amylin that acts in conjunction with insulin
    • ↓ release of glucagon
    • delays gastric emptying
  • Clinical use
    • type I and II DM
  • Toxicity
    • hypoglycemia
      • if given with insulin
    • nausea
    • diarrhea
GLP-1 analogs
  • Drugs
    • exenatide
  • Mechanism
    • GLP-1 is an incretin released from the small intestine that aids glucose-dependent insulin secretion
      • basis for drug mechanism is the observation that more insulin secreted with oral glucose load compared to IV
    • exenatide is a GLP-1 agonist
      • ↑ insulin
      • ↓ glucagon release
    • the class of dipeptidyl peptidase inhibitors ↓ degradation of endogenous GLP-1
      • e.g.) sitagliptin, -gliptins 
  • Clinical use
    • type II DM
  • Toxicity
    • nausea, vomiting
    • pancreatitis
    • hypoglycemia
      • if given with sulfonylureas
SGLT-2 Inhibitors
  • Drugs 
    • canagliflozin
    • empagliflozin
  • Mechanism
    • glucose is reabsorbed in the proximal tubule of the nephron by the sodium-glucose cotransporter 2 (SGLT2)
    • SGLT2-inhibitors lower serum glucose by increasing urinary glucose excretion
    • the mechanism of action is independent of insulin secretion or action
  • Clinical use
    • type II DM
  • Toxicity
    • dehydration
    • urinary and genital infections


Qbank (6 Questions)

(M1.EC.1) A 45-year-old woman presents to your office with a serum glucose of 250 mg/dL and you diagnose diabetes mellitus type II. You intend to prescribe the patient metformin, but you decide to order laboratory tests before proceeding. Which of the following basic metabolic panel values would serve as a contraindication to the use of metformin? Topic Review Topic

1. K+ > 4.0
2. Na+ > 140
3. HCO3- > 30
4. Glucose > 300
5. Creatinine > 2.0

(M1.EC.1) A 45-year-old African-American male presents to the family medicine physician to assess the status of his diabetes. After reviewing the laboratory tests, the physician decides to write the patient a prescription for miglitol and states that it must be taken with the first bite of the meal. Which of the following bonds will no longer be cleaved when the patient takes miglitol? Topic Review Topic

1. Phosphodiester bonds
2. Glycosidic bonds
3. Peptide bonds
4. Cystine bonds
5. Hydrogen bonds

(M1.EC.70) A patient presents to the emergency room in an obtunded state. The patient is a known nurse within the hospital system and has no history of any medical problems. A finger stick blood glucose is drawn showing a blood glucose of 25 mg/dL.

The patient's daughter immediately arrives at the hospital stating that her mother has been depressed recently and that she found empty syringes in the bathroom at the mother's home. Which of the following is the test that will likely reveal the diagnosis? Topic Review Topic

1. Genetic testing
2. C-peptide level
3. 24 hr cortisol
4. Fasting blood glucose
5. Urine metanephrines

(M1.EC.75) A simple experiment is performed to measure the breakdown of sucrose into glucose and fructose by a gut enzyme that catalyzes this reaction. A glucose meter is used to follow the breakdown of sucrose into glucose. When no enzyme is added to the sucrose solution, the glucose meter will have a reading of 0 mg/dL; but when the enzyme is added, the glucose meter will start to show readings indicative of glucose being formed. Which of the following diabetic pharmacological agents, when added before the addition of the gut enzyme to the sucrose solution, will maintain a reading of 0 mg/dL? Topic Review Topic

1. Insulin
2. Glyburide
3. Metformin
4. Acarbose
5. Exenatide

(M1.EC.107) A 55-year-old male is hospitalized for acute heart failure. The patient has a 20-year history of alcoholism and was diagnosed with diabetes mellitus type 2 (DM2) 5 years ago. Physical examination reveals ascites and engorged paraumbilical veins as well as 3+ pitting edema around both ankles. Liver function tests show elevations in gamma glutamyl transferase and aspartate transaminase (AST). Of the following medication, which most likely contributed to this patient's presentation? Topic Review Topic

1. Glargine
2. Glipizide
3. Metformin
4. Pioglitazone
5. Pramlintide

(M1.EC.201) A 53-year-old male presents to your office for a regularly scheduled check-up. The patient was diagnosed with type II diabetes mellitus two years ago. To date, diet, exercise, and metformin have failed to control his elevated blood glucose. Past medical history is also significant for hypertension. The patient does not smoke or use cigarettes. Laboratory values show a hemoglobin A1c (HbA1c) of 8.5%. You decide to add sitagliptin to the patient’s medication regimen. Which of the following is the mechanism of action of sitagliptin? Topic Review Topic

1. Inhibits degradation of endogenous incretins
2. Inhibits alpha-glucosidases at the intestinal brush border
3. Activates transcription of PPARs to increase peripheral sensitivity to insulin
4. Depolarizes potassium channels in pancreatic beta cells
5. Increases secretion of insulin in response to oral glucose loads and delays gastric emptying

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