The Impact of a Decade of Changing Treatment on Rates of Severe Hypoglycemia in a Population-Based Cohort of Children with Type 1 Diabetes

Bulsara MK, Holman CD, Davis EA, Jones TW. Diabetes Care. 2004;27:2293-2298.

Many aspects of care in type 1 diabetes have changed over the past 10 years. Management goals and educational methods have evolved, new insulins have become available, multiple-injection regimens and pump therapy have been increasingly used, and glucose-monitoring technologies have become more advanced. The purpose of this study was to examine changes in the incidence of severe hypoglycemia in children with type 1 diabetes relative to changes in treatment in a large cohort over 10 years, as well as to determine associated risk factors for severe hypoglycemic episodes. Treatment and practice changes over the decade included using more injections per day, using an insulin pump in some patients, and emphasizing strict glycemic targets.

The large cohort studied consisted of 1335 children with type 1 diabetes (≤18 years of age; mean age: 9.5 years) treated at Princess Margaret Hospital for Children in Perth, Western Australia from 1992 to 2002. Patients were seen every 3 months and followed for a mean of 4.7 years (range 0 to 10.7 yrs). Data were collected prospectively during clinic visits. Severe hypoglycemia was defined as a hypoglycemic episode leading to loss of consciousness or seizure.

Although the incidence of severe hypoglycemia increased by 18% per year over the first 5 years (P<0.0001), no significant additional change occurred over the last 5 years of the study period (P=0.962). Thus, the incidence of severe hypoglycemia plateaued after 5 years, while the A1C continued to decline significantly at a rate of 0.2% per year (P<0.0001). After adjusting for age and sex, a decrease in A1C was associated with a higher risk of severe hypoglycemia. In a multivariate analysis, children with A1C <9% had rates that were 3 to 4 times higher compared with those of children with A1C >11%.

Despite a lower mean A1C compared with patients on insulin injections, patients receiving pump therapy had a significantly lower rate of hypoglycemia. However, it should be noted that a much smaller number of patients in the cohort were receiving pump therapy (as compared with patients receiving multiple daily injections), and they were followed for a shorter period of time. No significant differences in the incidence of hypoglycemia were found between patients treated with a more frequent injection regimen (≥3 vs 2 injections of regular insulin per day or >2 vs 2 injections of insulin analog per day).

A number of risk factors were found to be associated with severe hypoglycemic episodes, including lower A1C, male sex, age, higher total insulin dose, and lower socioeconomic status of parents. In particular, boys aged 13 to 18 years were at significantly higher risk for hypoglycemic episodes compared with girls.