Long term efficacy of a pen injector

A review of 25 years' experience with the NovoPen family of insulin pens in the management of diabetes mellitus

NovoPen, the first insulin pen, was introduced in 1985. This review article is an update of a review paper published in 2006 on 20 years' use of the NovoPen family of insulin pens in the management of diabetes mellitus. The literature searches conducted in the earlier review article were updated with search results for new articles published since April 2005. This was followed by an iterative search of references cited in identified publications and by searches of abstracts from proceedings of major international diabetes conferences since 2005. Most of the original studies identified in the 2006 review showed that insulin regimens using the NovoPen family of insulin pens were at least as effective (and in some cases superior) in maintaining glycaemic control and were as safe (in terms of hypoglycaemia) as conventional insulin regimens employing vials and syringes. Most patients preferred the various NovoPen insulin pens over vials and syringes, with some evidence suggesting that the use of discreet devices, such as those of the NovoPen family, facilitates intensive insulin therapy regimens, thereby helping to improve lifestyle flexibility. The new search results showed that the current generation of the device for the adult population, NovoPen 4, retains these benefits and further meets patients' needs by improving ease of use, convenience and discretion, which may be particularly important for those with manual dexterity, visual or auditory impairments. There was also evidence that healthcare professionals would be more likely to recommend NovoPen 4 to their patients than other devices. The recently introduced NovoPen Echo, designed specifically for the paediatric population, combines half-increment dosing with a memory function that can be used to retrieve information about the time and amount of the last dose, potentially reducing the fear of double dosing or missing a dose. Evidence obtained from the new searches suggested that paediatric patients, their parents and healthcare professionals were highly satisfied with NovoPen Echo overall, with most paediatric patients rating it their favourite pen compared with other insulin pens. In conclusion, new data published over the last 5 years on the use of NovoPen devices add to the large body of published evidence supporting the patient-related benefits of durable insulin injection pens in the treatment of diabetes since the first such pen was introduced in 1985. Together, the benefits of NovoPen are considered likely to improve both patients' quality of life and their compliance with therapy.

A Review of 20??Years??? Experience with the Novopen?? Family of Insulin Injection Devices

NovoPen, the first insulin pen injector, was introduced in 1985. This article reviews the published evidence over two decades of use of the NovoPen family of injection devices in diabetes management. A search for NovoPen publications from 1985 onwards was conducted in the following databases: MEDLINE/PubMed, Cochrane Database of Systematic Reviews, American College of Physicians Journal Club, Database of Abstract Reviews and Effects, and Cochrane Controlled Trials Register. Publications were examined and underwent a selection process to identify studies of NovoPen devices (NovoPen [1], NovoPen 2, NovoPen 1.5 and NovoPen 3) in the diabetes/insulin therapy area that contained evidence of the effects of NovoPen in a variety of categories. Of the studies identified, most showed that insulin regimens using the NovoPen family of devices are at least as effective (and in some cases superior) in maintaining glycaemic control and are as safe (in terms of hypoglycaemia) as conventional insulin regimens employing syringes. The published evidence identified also showed that insulin administration via NovoPen devices was for most patients easier, more convenient and quicker than with conventional syringes and that most patients preferred the various NovoPen devices over syringes. There was also some evidence that the use of discreet devices, like those of the NovoPen family, facilitates adherence to intensive insulin therapy regimens, helps to improve lifestyle flexibility and reduces injection pain compared with conventional syringe-based regimens. Together these benefits of NovoPen devices are considered likely to improve both patients' quality of life and compliance with therapy. In conclusion, a large body of published evidence accumulated over the past two decades testifies to the patient-related benefits of the NovoPen family of insulin injection devices in the treatment of diabetes.

Inadequate suspension of neutral protamine Hagendorn (NPH) insulin in pens

BACKGROUND

Neutral protamine Hagedorn (NPH) insulin is one of the most commonly used insulins in insulin pens. NPH in pen cartridges is in a two-phase solution with either a solvent or a short-acting insulin, and needs adequate mixing for complete resuspension. We assessed whether NPH insulin is accurately resuspended by patients and the association of suspension errors with diabetes control.

METHODS

109 patients (39 with type 1 diabetes) who had received conventional diabetic education had the NPH content of their cartridges measured by an optical system; a control cartridge was designated as 100%. A questionnaire was used to assess clinical details and insulin suspension habits. After the information about residual insulin error was known, all 109 patients were instructed to resuspend their insulin by rolling and tipping the pen 20 times. 52 patients were randomly selected to have cartridges re-analysed 3 months or 6 months later and to complete another questionnaire.

FINDINGS

Only 10 (9%) of 109 patients tipped and rolled their pen more than ten times. NPH insulin content ranged from 5% to 214% and varied by more than 20% in 71 (65%) of 109 cartridges. There was no relation between inadequate suspension and the frequency of hypoglycaemic episodes (r=0.2, p=0.08). For all patients, there was a correlation between the absolute error of NPH suspension and cycles of rolling and tipping the pen (r=-0.23, p<0.05). After education on resuspending the pen's contents, data were available from 44 of 52 patients; suspension errors decreased in 35 (80%), were unchanged in three (7%), and increased in six (13%). The 35 patients with improved NPH insulin suspension had fewer mean hypoglycaemic episodes per month compared with the previous period (0.4 [SD 0.1] vs 1.0 [0.3], p<0.05). Mean HbA1c values in patients with improved suspension quality did not differ from baseline (8.4% [0.3] vs 8.9% [0.4], p=0.07). Mixing of NPH insulin by a mechanical device showed that at least 20 cycles were necessary before complete resuspension was obtained.

INTERPRETATION

Inadequate NPH insulin suspension is common. We recommended that patients tip pens that contain NPH insulin at least 20 times, since inadequate mixing may impair diabetes control.

Metabolic control, quality of life, and negative life events: a longitudinal study of well-controlled and poorly regulated patients with type 1 diabetes after changeover to insulin pen treatment

In a previous study of a group of 74 patients with Type I diabetes, quality of life was found to be consistently enhanced a year after transition to multiple injection therapy with the insulin pen, whereas metabolic control (HbA1C) only improved moderately. The aim of the present investigation was to examine quality of life, recent life events, and metabolic control longitudinally in this original study group over a 5-year period beginning 1 year after transition to the insulin pen. Multiple analysis of variance with a repeated-measures design was used to analyze the data longitudinally and compare metabolic control in subgroups of well-controlled and poorly regulated patients during the study period. For the group as a whole, quality of life was found to change only moderately, whereas metabolic control deteriorated significantly across time following transition to the insulin pen. The two subgroups exhibited distinct differences, however, in quality of life, recent life events, and metabolic control patterns. These findings are discussed in terms of the clinical suitability of a multiple injection regimen.