Type 2 diabetes has a number of drug treatment options to be taken by mouth known as oral antihyperglycemic drugs or oral hypoglycemic drugs.
Oral diabetes drugs are usually reserved for use only after lifestyle measures have been unsuccessful in lowering glucose levels to the target of an HbA1c below 7.0%, achieved through an average glucose reading of around 8.3-8.9 mmol/L (around 150-160 mg/dL). The lifestyle measures that are critical to type 2 diabetes management are diet and exercise, and these remain an important part of treatment when pills are added. People with type 1 diabetes cannot use oral pills for treatment, and must instead take insulin.
How do oral drugs lower glucose levels?
Metformin is the most widely used oral antihyperglycemic drug and reduces the amount of glucose released by the liver into the bloodstream. Oral antihyperglycemic drugs have three modes of action to reduce blood glucose levels:
- Secretagogues enhance insulin secretion by the pancreas
- Sensitizers increase the sensitivity of the peripheral tissues to insulin
- Inhibitors impair gastrointestinal absorption of glucose.
Each class of antihyperglycemic drug has a different adverse event or safety profile, and side effects are the main consideration when it comes to choosing a medication. Possible side effects range from weight gain, through gastrointestinal ones such as diarrhea, to pancreatitis and more serious problems. Hypoglycemia is also a possible adverse event.
What oral drugs are available for type 2 diabetes?
No one particular choice of oral hypoglycemic is considered the most effective form of treatment – the decision over which drug to use is instead based on:
- Consideration of the adverse side effects
- Convenience and overall tolerability
- Personal preference.
In reality, weighing up each drug is something to do in partnership with a prescriber – guidelines partly drawn up by the American Diabetes Association list a great number of advantages and disadvantages for each of the available drug treatments, including the consideration of cost. The use of a single drug can be escalated to combination therapy with a second drug in an effort to improve glycemic control. Metformin is usually the first treatment offered, however, and it is the most widely used oral antihyperglycemic. Metformin is a sensitizer in the class known as biguanides; it works by reducing the amount of glucose released by the liver into the bloodstream and increasing cellular response to insulin. A metformin pill is usually taken twice a day. This drug is a low-cost antihyperglycemic with mild side effects that can include diarrhea and abdominal cramping. Metformin is not associated with weight gain or hypoglycemia.