It is widely believed that taking a medication once a day is preferable to multiple doses. Certainly it is more convenient to take something only once a day. If you can assume that you get all the benefit of the medication this way, then once a day is a real advantage. For a medication like thyroxine (the thyroid hormone), taking a pill once a day is sufficient to give all the benefit. For a medication like insulin, which needs to be injected, it is attractive to think about taking it only once a day. Unfortunately it is not possible to get all the benefits from insulin by taking it only once a day. Unlike thyroxine, the levels of insulin in a person's body need to go up and down throughout the day, depending on whether the person is eating or resting or exercising.

Yet, there is a once-a-day form of insulin available. But a new study from England found that patients taking twice-daily NPH insulin had better glucose control, less hypoglycemia, and greater satisfaction with their treatment compared with once-daily ultralente insulin.

The study involved 79 patients with type 2 diabetes who were not adequately controlled on oral medication and therefore ready to begin insulin therapy. It was a crossover study, meaning that all patients used one type of insulin for 6 months and then switched to the other type for 6 months. Patients receiving twice-daily NPH insulin:

• Had significantly lower HbA1c readings (9% vs 9.7%)
• Had fewer hypoglycemic episodes requiring third-party help

Patients felt better and reported better quality of life on insulin treatment of either type but preferred twice-daily NPH insulin. The data for both groups also showed that:

• Weight gain was not significant.
• Blood pressure was not affected.
• Plasma triglycerides levels fell in proportion to improvement in glucose control.