Reducing injection pain in children and adolescents with type 1 diabetes : Studies on indwelling catheters and injection needles

Abstract: Insulin injections can be painful for many children, especially when using multiple daily injections. To reduce this procedural pain we in 1985 designed ao indwelling catheter for subcutaneous use when injecting insulin. This catheter has been well accepted by our patients. The aims of the present studies have been to further investigate the problems of pain associated with insulin injections in children and adolescents and to study side effects, metabolic control, and insulin absorption when using indwelling catheters (Insuflon®, Maersk Medical, Lynge, Denmark). Side effects and indwelling times were studied at home using questionnaires.Injection pain and needle phobia were studied using 10 cm VAS scales. Metabolic control was studied in a 10-week crossover study and insulin absorption with the help of an uncollimated gamma camera and 125I-insulin.The mean indwelling time was 4.8 ± 2.2 (range 0.5-17) days. Fixation problems and local redness at the insertion site were the most frequent side effects. No major infections requiring surgical or antibiotic treatment occurred. In the questionnaire of recalled pain, the VAS score of injections (median and quartiles) with syringes was 1.9 (1.1,3.5) cm, with pens 0.4 (0.2,1.3) cm, with indwelling catheters 0.4 (0.2, I. 7) cm, when taking a pump bolus dose 0.0 cm (0.0, 0.0), and when talcing a blood glucose test 0.7 (0.1, 2.4) cm. The injection pain and needle phobia declined with increasing age but some, both yOlmg children and teenagers, regarded the injection pain as almost unbearable. In the crossover study we found no significant difference between the arms with and without Insuflon in HbA1c, 24 hour profiles of blood glucose or serum free insulin. In the absorption study the patients used the same indwelling catheter for injections of short-acting insulin for 4 days. We found no significant difference in residual activity of 125 I-insulin after 60 min. or time to 50% remaining activity between injections day 1, 3 and 5, nor between catheter and ordinary injections on day 1, 3 and 5, respectively. HbA1c correlated significantly both to T-50% and residual activity of 125 I-insulin after 60 min. In the randomized multicenter study using Insuflon from the onset of diabetes, injection pain and parental pre-injection anxiety decreased from day 1-15 in both groups (in average 4.1 injections/day). Pain (median 1.7 cm vs. 2.7 cm, p=0.002) and parental pre-injection anxiety (1.2 cm vs. 2.9 cm, p=0.016) was lower for Insuflon users vs. ordinary injections. Talcing injections (including insertiug Insuflon) was found less problematic in the Insuflon group (1.6 cm vs. 3.3 cm, p=0.009). During the 6 month follow-up injection pain and injection problems were significantly lower in the Insuflon group. When comparing pen injector needles, the median VAS score ranged from 0. 7 cm to 1.2 cm in the first study where 27G and 28G needles were compared (n.s. ). In the following study, 280; 29G and 30G needles scored from 1.5 cm to 2.8 cm (n.s.). Placebo injections scored 0.1 cm (p=0.0001). Leakage of insulin was found in 14% of abdominal and 25% of thigh injections (p=0.0001) with no difference between the needles. VAS scores were higher in the later study which may be explained by the adding of faces to VAS, increasing the range of scores.In summary, most patients find the pain when injecting insulin quite small but for some it is almost unbearable. Needle diameter is of less importance for the expedenced injection pain. When using indwelling catheters from the onset of diabetes injection pain and pre-injection anxiety can be decreased significantly. The average indwelling time is 4-5 days and the frequency of side effects is low. Using indwelling catheters for up to 4 days does not affect the absorption of shmt-acting insulin when the catheter is inserted in an area free from lipohypertrophies and the long- and short-term metabolic control is not altered. We conclude that indwelling catheters can safely be used from the onset of diabetes to lessen injection pain in children and adolescents.