1 Diab Comp, 6:207-208

TECHNICAL REPORT

Prefilled Insulin Syrin es Can Be Kept Sterile for at Least 10 B ays When Kept Under Refrigeration Michael Kofler Ruth Omi- Wasserlauf Nechama Golani Stephen A. Bevger

INTRODUCTION

N on-insulin-dependent diabetes mellitus (NIDDM) is one of the most common chronic diseases associated with aging.’ Over a period of time, many such individ-

uals will show decreased insulin production, there- fore requiring supplemental insulin for adequate blood glucose control. Legal blindness is estimated to be 25 times more common in diabetic patients than in nondiabetic individuals.2 Among insulin-dependent diabetes mellitus (IDDM) patients greater than 55 years of age, the problem of legal blindness is approxi- mately 12%.3 LegaI blindness is approximateIy twice as prevalent among IDDM patients as among NIDDM patients;3 yet because NIDDM accounts for almost 93% of diabetes, there are probably as many people with NIDDM blindness as with IDDM and blindness.4 Many of these individuals, especially those with ad- vanced age who live alone and have impaired vision, need help to fill their insulin syringes from insulin vials. Thus, the help of another person is needed, as many of these patients need more than one injection of insuIin per day. In many cases it is impossible for this care provider to inject insulin more than once

Diabetes Unit (M.K.) and the Department of Microbiology, Tel- Aviv Sourasky Medical Center, Tel-Aviv, Israel

Reprint requests to be sent to: Dr. Michael Koffler, Diabetes Unit, Tel-Aviv Sourasky Medical Center, lchilov Hospital, 6 Weizman Street Tel-Aviv 64239, Israel.

daily in the patient’s home, and for many of the pa- tients it is difficult to leave home once or twice daily to receive medication. Pen devices for insulin injec- tion are now available with cartridges of long acting and premixed insulin, and the new pen injectors have a click device which enables people with poor vision to draw up accurate doses of insulin. But these pen devices are not available everywhere, they are more expensive, and patients frequently need doses of in- sulin which are not available when premixed insulin is used. Prefilled insulin syringes stored at home offer a perfect solution for many patients who can inject insulin but cannot prepare the proper dosage. In such cases, they need only inject themselves with insulin, a relatively simple procedure. Prefilled syringes are pharmacologically stable for up to 3 weeks when kept in a refrigerator.5

The aim of this study was to evaluate the sterility of insulin and syringes when they were kept under refrigeration for up to 10 days. To our knowledge no similar study has previously been published.

METHODS AND RESULTS

Each day 4 syringes (B-D micro-fine IV) were filled with 10 units of insulin, 2 syringes with rapid-acting insulin (velosulin human, Nordisk) and 2 syringes with intermediate-acting insulin (Insulatard human, Nordisk) by a registered nurse from the Diabetes Unit. The prefilled insulin syringes were kept in a refrigera- tor (4°C) for up to 10 days.

0 1992 ]ournal of Diabetes and Its Complications 0891-6632/92/$5.00

208 KOFFLER ET AL. ] Diab Camp 1992; 6:3

After 10 days the insulin samples from each syringe were cultured concurrently in a) brain heart infusion broth (pH 7.4, Oxoid, Ltd., Basingstoke, Hants, Eng- land) and b) in thioglycollate brain infusion broth (Fluid thioglycollate medium, DIFCO Laboratories, Detroit, MI). The samples were incubated at a temper- ature of 37°C under aerobic and anaerobic (Gas Pat) conditions for up to 7 days, with a daily check for growth. No signs of bacterial growth were evident in any of the specimens. In other words, the insulin samples remained sterile.

We conclude that it is safe to maintain prefilled insulin syringes under refrigeration for up to 10 days.

REFERENCES

1. Wingard DL, Sinshimer P, garret-Conner EL, McPhil- lips JB: Community-based study of prevalence of NIDDM in older adults. Diabetes Cure 13(suppl 2):3-8, 1990.

2. Palmberg PF: Diabetes retinopathy. Diabetes 26:703-709, 1977.

3. Klein R, Klein BEK, M&s SE: Visual impairment in dia- betes. Ophthalmology 91:1-9, 1984.

4. The Carter Center of Emory University: Closing the gap: The problems of diabetes mellitus in the United States. Diabetes Care 8:391-406, 1985.

5. American Diabetes Association: Position Statement. Clinical Practice Recommendations, American Diabetes Association 1990-91. Diabetes Cure 14(suppl 2):30-33, 1991.