1. Results Insulin Treatment of BBDP Rats Results (cont) Optimization of Insulin Treatment for Spontaneous Type 1 Diabetes (T1D) in BBDP/Wor Rats Barak Yahalom, Shane K. Duclos, Dennis L. Guberski, Christian W. Grant and Joan F. Flanagan Biomedical Research Models, Inc., Worcester, MA Introduction New long acting types of insulin capable of maintaining blood glucose levels within a near- normal range are in great demand for use in rodent models of T1D. However, standardized protocols (SP) for maintaining normoglycemia in preclinical diabetic rodent models are lacking. Therefore, we evaluated the efficacy of new long acting insulins for maintaining glycemic levels in our spontaneous T1D BBDR/Wor rat colony. Factors considered in the development of this SP included both the type of insulin and treatment regimen relative to fed state. Cohorts of BBDP/Wor rats that exhibited chronic diabetes were used in these studies. Several types of insulins: protamine zinc (PZI; 90% beef, 10% pork), Lantus (glargine, rDNA), Levemir (detemir, rDNA) or ProZinc (protamine zinc, recombinant human) were evaluated by a single subcutaneous injection to maintain normoglycemia within a 24 hour period. Next, the optimum timing of insulin administration for glycemic control was compared when therapies were administered during the non- fed or fed state by measuring blood glucose levels every 2 - 4 hours over a 24 hour period. Our data show that the once daily injection of PZI targeted to 0.9U/100g body weight was superior for maintaining daily glycemic control in diabetic rats to both Lantus and Levemir when administered at the same dose. Interestingly, a comparable dose of ProZinc exhibited enhanced duration of normoglycemia compared to PZI. Moreover, similar to human treatment regimens, insulin administration just prior to fed-state with either PZI or ProZinc provided safer and longer daily glycemic control compared to insulin treatment at the non-fed state. In summary, once daily, subcutaneously injection of either Prozinc or PZI insulins, administered just prior to the fed-state, are effective at maintaining daily glycemic levels in spontaneously diabetic BBDP/Wor rats. This knowledge will allow for more accurate mimicking of that expected in human patients in our preclinical efficacy trials. Methods Animal Models BBDP/Wor Rats Chronic diabetic male rats Duration of 43-64 days Diagnosis of Diabetes Rats were screened 3x/week for glycosuria Animals with a positive glycosuria and serum glucose level of >250mg/dL were considered diabetic Insulin Treatment Protocols Insulins were injected subcutaneously (sc) at 0.9U/100g body weight Blood glucose levels were measured by handheld glucometer over a 24-hour period post insulin administration Factors considered: Type of insulin: PZI ® (protamine zinc Insulin;90% beef, 10% pork) Lantus ® (glargine, rDNA), Levemir ® (detemir, rDNA) ProZinc ® (protamine zinc, recombinant human) Timing of dose relative to fed state: Two hours before fed-state Six hours before fed-state Figure 1: Average Serum Glucose Among Diabetic Male BBDP/WOR Rats Treated with different insulin regimens. A) ProZinc Vs Levemir Insulin at 6 hours before fed state. B) PZI, Lantus and ProZinc at 2 hours before fed state Figure 1: (A) Groups of 10 diabetic male BBDP rats were treated with either a single dose of ProZinc (green squares) or Levemir (black triangles) at 6 hours before fed state. (B) A group of 8-10 diabetic male BBDP rats were treated with a single dose of PZI (red), Lantus (dark blue) or Prozinc(green) at 2 hours before fed state. Serum glucose levels were measured every 2 hours, except for (A) 1 time point was 10 hours apart. Mean +/- SEM are depicted. A single injection of Levemir at 0.9U/100g BW at 6 hours before fed state did not provide effective glycemic control. A single injection of Lantus at 0.9U/100g BW or 1.1U/100g BW (data not shown) at 2 hours before fed state did not provide effective glycemic control. A single injection of ProZinc was enhanced compared to PZI insulin to maintain normoglycemia control over 24 hours. PZI or Prozinc insulin were more effective when administered before fed state. Acknowledgements This work was funded by BRM, and performed by the Springfield facility technical staff Insulin administration just prior to fed-state with either PZI or ProZinc provided safer and longer daily glycemic control in BBDP/Wor rats compared to an early treatment at the non-fed state. Conclusion