Safety and Effectiveness of Insulin Pump Therapy in Children and Adolescents With Type 1 Diabetes

Leslie P. Plotnick, MD, Loretta M. Clark, RN, BSN, CDE, Frederick L. Brancati, MD, MHS, Thomas Erlinger, MD, MPH

Disclosures

Diabetes Care. 2003;26(4) 

In This Article

Research Design and Methods

All patients who were followed in the Pediatric Diabetes program of the Johns Hopkins Hospital and started insulin pump therapy between 1 January 1990 and 31 December 2000 were included in this study. Medical records were reviewed for 95 patients, ages 4-18 years at pump start. The mean (± SD) age was 12.0 ± 3.1 years, and children under the age of 10 years comprised 29% of the group. There were 52 girls and 43 boys; 91 were Caucasian and 4 were African-American. Duration of diabetes at pump start was 5.6 ± 3.3 years. Frequency of blood glucose monitoring was 4.6 ± 1.7 times per day.

Patients and families chose insulin pump therapy for several reasons, including better control, less blood glucose variability, fewer injections, and improvement in lifestyle flexibility. Before insulin pump therapy was started, all patients and families needed to demonstrate a desire and ability for intensive management with multiple daily injections, frequent blood glucose monitoring, satisfactory record-keeping details, ability to make appropriate insulin dose adjustments, and accurate carbohydrate counting.

Before initiation of pump therapy, all patients and families were instructed in carbohydrate counting, including written assignments to document learning. They also were taught the mechanics of pump use and wore a demonstrator pump with saline for 2-5 days. Some parents also chose to wear a demonstrator pump, although this was not a requirement. Both Disetronic (St. Paul, MN) and MiniMed (Northridge, CA) insulin pumps were used. The patient and family chose the pump brand.

At the time of pump placement, all patients were admitted to the Johns Hopkins Hospital for 24-48 h. During the admission, in addition to frequent blood glucose monitoring (usually every 2 h, including preprandial, postprandial, and overnight levels), insulin doses were determined for basal rates, insulin-to-carbohydrate ratios at each meal, and correction boluses. These doses were adjusted and refined based on blood glucose responses. Nutrition evaluation and assessment were also done. Patients recorded all blood glucose levels, basal and bolus doses, and carbohydrate grams on pump recording sheets. Initially, all insulin used was buffered regular. The majority of patients used lispro insulin when it became available.

Risks of pump use and risk prevention were discussed in depth with all patients. This included site infections and the potential of increased risk of hyperglycemia, ketosis, and DKA. Hypoglycemia awareness, prevention, and treatment were also reviewed. Problem-solving strategies were discussed, such as potential mechanical problems (e.g., air bubbles, kinked infusion sets, and dislodged tubing) that could cause lack of expected insulin delivery. After the pump start, all patients had daily phone contact with the diabetes nurse educator for 3-7 days and then fax or phone contact (once or twice per week) for at least the next 1-2 months. The first follow-up appointment was within 2 months of the pump start and always included a nutrition evaluation. After the first follow-up appointment, visits took place at the usual clinic schedule every 3-4 months. These visits included medical, nurse educator, and nutrition evaluation and assessment. Glycemic goals were discussed at each clinic visit, and if not met, more intensive diabetes team involvement was recommended.

All data were obtained by chart review by the advanced practice registered nurse (certified diabetes educator). Data were collected for a period of 6-12 months before initiation of the insulin pump and for as long as we followed each patient in our clinic and he or she remained on pump therapy, or until the end of the study observation period (31 December 2000). After graduation from high school, patients transitioned care to adult endocrinology. The study was approved by the Johns Hopkins Joint Committee on Clinical Investigation.

Information was obtained at each visit (generally every 3 months) both before and after pump therapy was started. This information included height, weight, pubertal stage, HbA1c, frequency of blood glucose monitoring, insulin doses, number of insulin injections per day (prepump), DKA, emergency department (ED) visits, hospitalizations, infusion site infections, and episodes of severe hypoglycemia (defined according to the Diabetes Control and Complications Trial protocol to include coma, seizures, or any other inability to self-treat).[4] In addition, we made a subjective assessment of parental availability to help with diabetes management. We assessed 41.5% of parents to be highly involved and 58.5% to be moderately involved.

HbA1c was measured at each visit by cation-exchange high-performance liquid chromatography (Variant; Bio-Rad Laboratories, Hercules, CA), with a nondiabetic range of 4.5-6.1%. Frequency of blood glucose monitoring was obtained by review of blood glucose records (either written or by downloading their meters) or by patient report. Number of insulin injections per day before pump placement was determined from the number of prescribed injections and patient records and report. Insulin doses were determined by prescribed doses, patient records and report, and pump memory of bolus doses and 24-h totals. Height was measured using a Harpendon stadiometer and weight by hospital balance-beam scales. Height and weight percentiles were determined by National Center for Health Statistics growth curves (https://www.cdc.gov/growthcharts). Parental availability to help with diabetes management was classified as moderate or high based on the subjective assessment of the advanced practice registered nurse’s experience with the family.

At each clinic visit, the number of severe hypoglycemia episodes, DKA episodes, ED visits, and hospitalizations that occurred since the prior clinic visit were recorded. DKA was defined as requiring intravenous fluids and insulin in the ED or during inpatient hospitalization. All ED visits and hospitalizations were counted, regardless of the reason. All self-reported site infections were included.

Incidence rates of complications were determined per 1,000 person-months of follow-up. All events were counted, including repeated events if they occurred. To account for effects of within-person correlation with repeated measures, we used clustered analysis for comparison of incidence rates before and after pump start and generalized estimating equations for all other comparisons, including linear trends between HbA1c and diabetes duration and HbA1c and age. To assess the independent impact of insulin pump use, all predetermined covariates were entered simultaneously into a multivariate model. All reported P values were two-sided. Analyses were conducted using STATA 7.0 (College Station, TX).

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