Miglitol, the first pseudomonosaccharide alpha-glucosidase inhibitor, smooths postprandial peak plasma glucose levels and thus improves glycaemic control, which is reflected in a reduced glycosylated haemoglobin (HbA1c) level. This oral antihyperglycaemic agent is indicated for the treatment of patients with type 2 diabetes mellitus. Miglitol is generally well tolerated and, unlike the sulphonylurea agents, is not associated with bodyweight gain or hypoglycaemia when administered as monotherapy. The drug is systemically absorbed but is not metabolised and is rapidly excreted via the kidneys. Clinical trials with miglitol (usually 50 or 100 mg 3 times daily) in patients with type 2 diabetes mellitus consistently demonstrated a significant improvement in glycaemic control for periods of 6 to 12 months. There were also marked reductions in postprandial serum insulin levels, although miglitol generally had no effect on fasting insulin levels. In comparative studies miglitol had similar efficacy to acarbose, but at lower therapeutic doses (50 and 100 mg 3 times daily, respectively). In addition, although sulphonylurea agents provided superior reductions in HbA1c levels, miglitol provided similar or superior reductions in fasting and postprandial plasma glucose levels. In combination with other oral antidiabetic agents or insulin, miglitol improved glycaemic control in patients in whom metabolic control was suboptimal despite dietary and pharmacological intervention. Most adverse events associated with miglitol treatment involve disturbances of the gastrointestinal tract (most common effects are flatulence, abdominal pain and diarrhoea). These symptoms are usually dose dependent, mild to moderate in severity, occur at the onset of treatment, decline with time and resolve promptly on discontinuation of the drug or with dosage adjustment. As monotherapy, miglitol is not associated with hypoglycaemia, but concomitant use with other oral antidiabetic agents may necessitate dosage adjustment of the other agents. Miglitol had no significant effects on renal, cardiovascular, respiratory or haematological parameters in long term studies. No dosage adjustments are required in elderly patients, in those with hepatic impairment or in those with mild to moderate renal insufficiency.
Conclusions: In long term, well designed trials miglitol reduces fasting and postprandial plasma glucose levels, thus improving glycaemic control, which is reflected in a reduced HbA1c level in patients with type 2 diabetes mellitus. Most adverse events associated with miglitol involve disturbances of the gastrointestinal tract. This agent is a useful first-line therapy in patients with type 2 diabetes mellitus insufficiently controlled by diet alone and as second-line or as adjuvant therapy in those insufficiently controlled with diet and sulphonylurea agents. Miglitol may prove particularly beneficial in elderly patients and those with hepatic impairment or mild to moderate renal impairment, in whom other oral antidiabetic agents are contraindicated or need to be used with caution.