Insulin and Low Blood Glucose

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Reduced hypoglycemia risk with insulin glargine: a meta-analysis comparing insulin glargine with human NPH insulin in type 2 diabetes, by J. Rosenstock and colleagues. Diabetes Care 28:950-955, 2005.

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

Hypoglycemia, or low blood glucose, can happen from time to time to everyone who has diabetes.

The symptoms of low blood glucose include:

• Shakiness
• Dizziness
• Sweating
• Hunger
• Headache
• Pale skin color
• Sudden moodiness or behavior changes
• Clumsy or jerky movements
• Seizure
• Difficulty paying attention, or confusion
• Tingling sensations around the mouth.

Hypoglycemia is sometimes called an insulin reaction. People with type 1 diabetes must take insulin to survive. When people with type 2 diabetes can’t get their blood glucose to a healthy level over time with diet, exercise, or pills, they are prescribed insulin. People with diabetes may have low blood glucose if their dose of insulin doesn't balance with their food or activity.

Why did the researchers do this particular study?

Previous studies have shown that certain types of insulin trigger low blood glucose more often than other types. The authors wanted to compare results of studies on two different types of insulin: NPH insulin and insulin glargine.

NPH insulin is an "intermediate-acting" insulin that is mixed with another substance so that the body absorbs the insulin over a period of time. NPH usually begins to work about 2 to 4 hours after being injected. It works strongest 4 to 10 hours after injection, and it keeps working for 10 to 16 hours. A shot of NPH in the evening keeps insulin in the body during the night and until the morning.

Insulin glargine is a "long-acting" insulin. It starts to lower blood glucose about 1 hour after injection and keeps working evenly for 24 hours.

The authors wanted to look at which type of insulin -- NPH insulin or insulin glargine -- caused low blood glucose more often in people with type 2 diabetes.

How was the study done?

The authors looked at the results of four studies that compared treatment with NPH insulin and treatment with insulin glargine in patients with type 2 diabetes. In each study, insulin glargine was taken at bedtime and NPH insulin was taken once or twice a day. The study times ranged from 24 to 52 weeks. The number of patients ranged from 460 to 756.

Who was studied?

A total of 2,304 patients with type 2 diabetes were included in these studies; 1,142 took insulin glargine and 1,162 took NPH insulin. All of the patients had type 2 diabetes for at least 2 years, were younger than 80 years of age, and had high blood glucose levels.

What did the researchers find?

Patients who took insulin glargine had a much lower risk of low blood glucose than the patients who took NPH insulin.

What were the limitations of the study?

This article only looked at the results of four studies, which is a very small number for this type of analysis.

The authors of this study have received money from a company that makes and sells a brand-name insulin glargine.

What are the implications of the study?

Insulin glargine may be much less likely to trigger low blood glucose than NPH insulin in patients with type 2 diabetes.

FOR MORE INFORMATION

Hypoglycemia

Kordella T: Hypoglycemia unawareness: can beta-blockers help? Diabetes Forecast, May 2004.