We developed a new experimental model of accelerated diabetes mellitus in the genetically susceptible diabetes-prone BB rat with the administration of the IFN-α inducer poly I:C. With this model, there was both an increased incidence and accelerated onset of insulin-dependent-diabetes in poly I:C–treated animals compared with saline-treated controls. All twelve rats administered poly I:C (5 μg/gm body weight 3 times/wk) developed diabetes by 57 days of age (100%) compared with 1 of 27 (3.7%) saline-treated controls. Furthermore, the development of diabetes was accelerated in the poly I:C–treated group (mean age ± SE at onset 52.8 ± 0.58 days) compared with saline-treated controls (89.3 ± 2.4 days, P < 0.01). Additionally, poly I:C–treated rats had higher mean serum IFN-α levels than saline-treated rats at weeks 2 and 3 of treatment (210 vs. 27 and 183 vs. 25 U/ml, respectively, P < 0.001). Poly I:C treatment of 5 Wistar rats, the parental strain, which is not susceptible to diabetes, did not result in insulitis, diabetes, or hyperglycemia. The histopathologic findings of insulitis and decreased immunoreactive islet insulin in poly I:C–accelerated diabetic BB rats and in BB rats with spontaneous diabetes suggest a similar pathophysiology.

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