Anti-Diabetic Drugs: Types and Mechanism

Anti-Diabetic drugs are the medications which are developed to maintain or control the blood glucose levels in Diabetic patients. Diabetes is one of the most common diseases in the world and it can affect each and every organ of the body. The invention of anti-diabetics acted as a life saver for many people across the planet. 

Type of Anti-Diabetic Drugs

There are two types of Diabetes mellitus and both have different treatments.

• Type 1 diabetes mellitus - Insulin replacement
• Type 2 diabetes mellitus - Oral agents ( Metformin is first line), non insulin injectables, insulin replacement , weight loss.
• Gestational Diabetes mellitus - Insulin replacement if nutrition therapy and exercise alone fail.

Insulin

Rapid Acting Insulin

The peak is for 1 hour

• Lispro
• Aspart
• Glulisine

Short Acting

The peak is for 2-3 hour

• Regular

Intermediate Acting

The peak is 4-10 hour 

• NPH

Long Acting

There is no real peak

• Detemir
• Glargine

Also Read: Anti-Cancer Drugs

Important Mnemonics in Pharmacology

Oral Antidiabetic Drugs

• Biguanides- Metformin
• Thiazolidinediones- Pioglitazone, Rosiglitazone
• Sulfonylureas- 
  • 1st generation- Chlorpropamide, Tolbutamide
  • 2nd generation- Glipizide, Glyburide
• Meglitinides -Nateglinide, repaglinide
• GLP-1 analogs- Exenatide, Liraglutide
• DPP-4 inhibitors- Linagliptin, saxagliptin, sitagliptin
• Sodium-glucose cotransporter 2 inhibitors (SGLT-2 inhibitors)
• Alpha-glucosidase inhibitors- Acarbose, Miglitol
• Amylin analogs- Pramlintide

Also Read: Autacoids- An Overview

Anti-Diabetic Drugs Mechanism of Action

Insulin

Mechanism of Action

The mechanism of action of insulin is by binding the insulin receptors (tyrosine kinase activity), causing :

• Liver: increased glucose storage as glycogen
• Muscle: Increased glycogen and protein synthesis
• Fat: Increased triglyceride storage
• Cell Membrane: Increased potassium intake

Adverse Effects of Insulin

• Hypoglycemia
• Lipodystrophy
• Hypersensitivity reactions (rare)
• Weight gain

Also Read: Pharmacokinetics: Absorption, Distribution, Metabolism, Excretion

Biguanides

The drug included in this category is Metformin.

Mechanism of Action

Increases insulin sensitivity by inhibiting mGPD, leading to inhibition of hepatic gluconeogenesis and the action of glucagon, causing increased glycolysis and peripheral glucose uptake, ultimately increasing insulin sensitivity.

Adverse Effects of Biguanides

• GI upset
• Lactic Acidosis (used with caution in patients with renal insufficiency)
• Vitamin B12 deficiency
• Weight loss (often desirable effect)

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Thiazolidinediones

Mechanism of Action

The drugs included in this category are Pioglitazone and Rosiglitazone. The mechanism of action is by activating PPAR-gamma (a nuclear receptor), leading to increased insulin sensitivity and levels of adiponectin, causing regulation of glucose metabolism and fatty acid storage. (increase insulin sensitivity).

Adverse Effects of Thiazolidinediones

• Weight gain
• Edema
• Heart failure
• Increased risk of fractures
• Delayed onset of action (several weeks)
• Rosiglitazone: Increased risk of MI and cardiovascular death

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Sulfonylureas

The drugs are:1st generation- chlorpropamide, tolbutamide, and 2nd generation- glipizide, glyburide.

Mechanism of Action

The mechanism of action is that it increases insulin secretion by closing K+ channels in the pancreatic B cell membrane, leading to cell depolarization and insulin release via increased Calcium influx.

Adverse Effects of Sulfonylureas

• Disulfiram-like reaction with first-generation sulfonylureas(rare effect)
• Hypoglycemia (increases risk in renal insufficiency)
• Weight gain

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Meglitinides

The drugs are Nateglinide and Repaglinide. The mechanism of action is by increasing insulin secretion by closing K+ channels in the pancreatic B cell membrane, leading to cell depolarization and insulin release via increased Calcium influx.

Adverse Effects of Meglitinides

• Hypoglycemia (increases risk in renal insufficiency)
• Weight gain

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GLP-1 Analogs

The drugs are Exenatide and Liraglutide.

Mechanism of Action

• Decreased glucagon release
• Decreased gastric emptying
• Increased glucose-dependent insulin release

Adverse Effect of GLP-1 Analogs

• Nausea
• Vomiting
• Pancreatitis
• Weight loss (often desirable effect)
• Increased Satiety (often desirable effect)

Also Read: Pharmacokinetics: Absorption, Distribution, Metabolism, Excretion

DPP-4 Inhibitors

The drugs are Linagliptin, Saxagliptin, and Sitagliptin.

Mechanism of Action

The mechanism of action is by inhibiting the DPP-4 enzyme that deactivates GLP-1, leading to decreased glucagon release and decreased gastric emptying, causing increased glucose-dependent insulin release.

Adverse Effects of DPP-4 Inhibitors

• Respiratory and urinary infections
• Weight neutral
• Increased satiety (often desirable effect)

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SGLT-2 Inhibitors

The drugs are Canagliflozin, Dapagliflozin and Empagliflozon.

Mechanism of Action

The mechanism of action is by blocking the reabsorption of glucose in the proximal convoluted tubule.

Adverse Effect of SGLT-2 Inhibitors

• Glucosuria (UTIs and vulvovaginal candidiasis)
• Dehydration (orthostatic hypotension)
• Weight loss
• Use with caution in renal insufficiency (decreased efficacy with decreased GFR)

Also Read: Antiarrythmic Drugs: Types, Uses and Side Effects

Alpha-glucosidase Inhibitors

The drugs are Acarbose and Miglitol.

Mechanism of Action

The mechanism of action is by inhibiting the intestinal brush-border alpha-glucosidases, causing delayed carbohydrate hydrolysis and glucose absorption, leading to decreased postprandial hyperglycemia.

Adverse Effects of Alpha-glucosidase Inhibitors

• GI upset
• Bloating
• Not recommended in renal insufficiency

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Amylin analogs

The drug is Pramlintide.

Mechanism of Action

• Decreased glucagon release
• Decreased gastric emptying

Adverse Effects of Amylin analogs

• Hypoglycemia
• Nausea
• Increased satiety (often desirable effect)

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