From the Guidelines
Acarbose works by inhibiting carbohydrate absorption in the upper small intestine, thereby reducing postprandial blood glucose levels. This is achieved by blocking enzymes called alpha-glucosidases that normally break down complex carbohydrates into simple sugars like glucose 1. When taken with meals, acarbose prevents the rapid breakdown of starches and sugars, resulting in a more gradual absorption of glucose into the bloodstream.
Mechanism of Action
The medication works locally in the digestive tract, rather than systemically in the body, which reduces the risk of hypoglycemia when used alone 1. However, it may cause digestive side effects like gas and bloating as undigested carbohydrates reach the large intestine. These side effects often improve with continued use as the body adjusts to the medication.
Clinical Use
Acarbose is suitable for patients who consume carbohydrates as their main food ingredient and experience postprandial hyperglycemia 1. It can be used in combination with other medications, such as biguanides, sulfonylureas, or insulin, to achieve better control of glucose metabolism. The recommended dose of acarbose is typically 300 mg/day, which has been shown to have a similar hypoglycemic effect to metformin 1500 mg/day in newly diagnosed patients with type 2 diabetes 1.
Safety and Efficacy
The risk of hypoglycemia is very low when acarbose is used alone, but it can occur when used in combination with other diabetes medications 1. In such cases, glucose or honey can be used to treat hypoglycemia, while dietary sucrose and starchy foods have a poor ability to correct hypoglycemia. Overall, acarbose is a useful medication for controlling glucose metabolism, particularly in patients with type 2 diabetes or prediabetes who experience postprandial hyperglycemia.
From the FDA Drug Label
Acarbose is a complex oligosaccharide that delays the digestion of ingested carbohydrates, thereby resulting in a smaller rise in blood glucose concentration following meals. The antihyperglycemic action of acarbose results from a competitive, reversible inhibition of pancreatic alpha-amylase and membrane-bound intestinal alpha-glucoside hydrolase enzymes Pancreatic alpha-amylase hydrolyzes complex starches to oligosaccharides in the lumen of the small intestine, while the membrane-bound intestinal alpha-glucosidases hydrolyze oligosaccharides, trisaccharides, and disaccharides to glucose and other monosaccharides in the brush border of the small intestine In diabetic patients, this enzyme inhibition results in a delayed glucose absorption and a lowering of postprandial hyperglycemia.
Acarbose works to control glucose metabolism by:
- Delaying carbohydrate digestion, which results in a smaller rise in blood glucose concentration after meals
- Inhibiting pancreatic alpha-amylase and intestinal alpha-glucosidase enzymes, leading to delayed glucose absorption and lowered postprandial hyperglycemia 2
- Reducing glycosylated hemoglobin levels in patients with type 2 diabetes mellitus, as a consequence of plasma glucose reduction Key points about acarbose's mechanism of action include:
- Competitive, reversible inhibition of enzymes involved in carbohydrate digestion
- Local action within the gastrointestinal tract, with low systemic bioavailability of the parent compound
- Additive effect when used in combination with other antidiabetic medications, such as sulfonylureas, insulin, or metformin 2
From the Research
Mechanism of Action
- Acarbose works by competitively inhibiting the alpha-glucosidases in the intestinal brush border, delaying the conversion of nonabsorbable dietary starch and sucrose into absorbable monosaccharides 3.
- This delay in carbohydrate absorption reduces postprandial blood glucose peaks 4, 5, 6.
- Acarbose specifically influences the absorption of starch and sucrose, but not lactose and glucose 3.
Effects on Glucose Metabolism
- Acarbose decreases postprandial plasma glucose excursions, reducing fasting and postprandial serum insulin, fasting plasma glucose, and hemoglobin A1c levels 4, 5, 6.
- It improves glycemic control in patients with non-insulin-dependent diabetes mellitus (NIDDM) managed with diet alone or with other antidiabetic therapy 4, 5, 6.
- Acarbose may also lower postprandial plasma insulin levels and decrease fasting plasma glucose, triglyceride, and/or cholesterol levels 6.
Therapeutic Benefits
- Acarbose is an effective first-line therapy for patients with newly diagnosed type 2 diabetes and can be used in combination with other antidiabetes agents 4.
- It reduces the risk of cardiovascular events in patients with impaired glucose metabolism, including those with impaired glucose tolerance and type 2 diabetes 7.
- Acarbose may also delay or prevent long-term vascular complications of diabetes 6.