Metformin Plus Inhaled Insulin or Glibenclamide Can Help Lower A1C to Target Levels

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An open, randomized, parallel-group study to compare the efficacy and safety profile of inhaled human insulin (Exubera) with glibenclamide as adjunctive therapy in patients with type 2 diabetes poorly controlled on metformin, by A.H. Barnett and colleagues. Diabetes Care 29:1818–1825, 2006

What is the problem and what is known about it so far?

Many patients with type 2 diabetes struggle to reach the A1C target goal of less than 7%. A1C is a measure of one’s average blood glucose level over a period of weeks or months.

Why did the researchers do this particular study?

Metformin is a drug that is commonly taken by patients with type 2 diabetes to lower their blood glucose levels. The researchers wanted to see if taking inhaled insulin or glibenclamide, in addition to metformin, would help patients with type 2 diabetes reach the target A1C goal.

Glibenclamide is another type of oral drug that helps lower blood glucose levels. Inhaled insulin comes in powder form and is inhaled through the mouth with a device similar to an asthma inhaler. Some patients prefer inhaled insulin because it doesn’t require taking a shot.

Who was studied?

Nearly 500 patients with type 2 diabetes who were taking metformin and had high A1C levels.

How was the study done?

One group of patients was given inhaled insulin and the other group was given glibenclamide in addition to their metformin. The patients were also grouped according to their A1C levels: the “moderately high” group had levels between 8% and 9.5% when the study started; the “very high” group had levels between 9.5% and 12%. The study lasted for 24 weeks.

What did the researchers find?

Both glibenclamide and inhaled insulin helped the patients lower their A1C levels. For patients with very high A1C levels, inhaled insulin had a greater effect.

Among patients with very high A1C levels, there were more cases of hypoglycemia reported by those who took inhaled insulin. Hypoglycemia is sometimes referred to as an “insulin reaction.” It can occur when too much insulin is taken, causing blood glucose levels to drop too low.

The patients who took inhaled insulin experienced mild coughing more often than the patients who took glibenclamide.

After 24 weeks, 37% of the patients who took inhaled insulin reached the A1C target goal of less than 7%; 31% of the patients who took glibenclamide reached the target goal.

What are the implications of the study?

Some patients with type 2 diabetes who take metformin still have problems with controlling their A1C and blood glucose levels. Taking inhaled insulin or glibenclamide in addition to metformin may help these patients.

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