Is insulin diluted when stored in water?

BACKGROUND: Insulin storage is a challenge in resource-poor countries. In Uganda, patients were noted to store insulin vials by submerging them in water. OBJECTIVE: To examine whether withdrawing insulin from a vial without adding air back causes a vacuum which allows water to enter the vial, resulting in insulin dilution. METHODS: Seven hundred units of insulin were withdrawn from forty 10 mL vials of 100 units/mL insulin [20 neutral protamine hagedorn (NPH), 20 regular]. In half, air was added back. The vials were weighed (baseline). Half of the vials (10 with added air, 10 without) were submerged in water for 24 h and then air-dried for 24 h. Vials that were not submerged sat at room temperature for 48 h. All vials were weighed 48 h from baseline. RESULTS: Addition of air did not impact the change in weight after submersion (air added: -0.002 ± 0.001 g or -0.2 ± 0.1 unit; no air added: -0.003 ± 0.000 g or -0.3 ± 0 unit, p = 0.57). In a subset of vials in which an additional 240 units were withdrawn before submersion for another 24 h, there was still no difference in weight change in those vials with air added (p = 0.2). CONCLUSION: Withdrawing insulin from a vial without adding air did not result in uptake of water or dilution of insulin in the submerged vial, although it made drawing up the insulin easier. This study did not address the larger concern of bacterial contamination of the rubber stopper during water storage.

Establishing the incidence and timing of hypoglycemia at a residential diabetes camp.

AIMS: To establish the incidence and timing of hypoglycemia at a week-long residential diabetes camp for children. We hypothesized that hypoglycemia would occur more frequently during the first two days of camp and following evening all-camp games. METHODS: 225 children (mean age 12.0 ±â€¯2.3 years, 56% female, mean hemoglobin A1c 8.4% [71.6 mmol/mol]) had blood glucose (BG) levels obtained before meals, at bedtime, and as needed to detect hypoglycemia. Insulin adjustments were made by medical staff according to camp protocol and at the discretion of medical staff during camper check-in. RESULTS: Mild hypoglycemia (BG 50-69 mg/dL [3.9 mmol/L]) occurred ≥ 1 time in 90% of campers while 43% had ≥ 1 episode of BG < 50 mg/dL (2.8 mmol/L). No episodes of hypoglycemia requiring glucagon occurred. More campers experienced ≥ 1 overnight hypoglycemia event during the first 48 hours of camp compared to later in the week (p = 0.01). Evening all-camp games did not impact hypoglycemia rates overnight. CONCLUSIONS: Nocturnal hypoglycemia occurred more frequently during the first two nights, establishing this period as high risk and supporting implementation of a standard protocol to lower insulin doses. Rates of hypoglycemia were unaffected by all-camp games, indicating current practices are effective at minimizing hypoglycemia.