Background: With the aim of evaluating the real consumption on insulin an analysis of its loss with use in clinical practice was carried out. The influence of this loss was investigated in the calculations of prevalence of diabetes (DM) initiating from the consumption of medication, the presumable repercussion in public health costs and possible alternatives.
Methods: Revision and analysis of the recipients used by a group of 58 insulin treated diabetics was carried out during a mean period of one month. The theoretic consumption, real consumption and the mean loss per each injection according to visual accuracy and the system employed were evaluated. A deduction was made of the autonomy by storing of insulin. A previous calculation concerning the prevalence of DM in Tarragona (548,900 inhabitants) according to consumption was corrected and an economic estimation of the loss demonstrated over public health costs of insulin during 1991 was made.
Results: The mean dose prescribed was 39.7 IU/day supplied in 2.4 injections/patient/day. At 30 days (27-35) 310 recipients were evaluated (115 vials/195 boxes). The mean real dose consumed was 53.3 IU/day and the mean loss per injection was 5.6 (25.5% of all the insulin supplied, 4.5% as remnants at the bottom of the recipient). A greater loss was observed by injection a) in patients with reduced sight (6.4 +/- 7.3 IU/5.5 +/- 4.5; NS) and b) in the users of syringes with dead space (5.8 +/- 4.7) with respect to those using an injector insulin pen (4.4 +/- 2.9; p < 0.01). The autonomy by domiciliary storage of insulin was of 103.7 days/patient (prescribed doses) and 78.6 (real consumption). A total of 7 diabetics (12%) had unused expired recipients. The prevalence of insulin treated DM in Tarragona was estimated as around 4.3-4.8/1,000 (2,360-2,635 inhabitants). The expense of loss was 36 million pesetas/year; 6.4 as depreciated remnants of insulin in the bottom of recipients.
Conclusions: There is a great loss of insulin in clinical practice which may be avoidable and which influences the public health costs for diabetes. An adequate educative strategy and system of injection independent of user ability would reduce the costs.