Poly (lactide-co-glycolide) (PLG) is one of the most widely used biodegradable synthetic polymer for sustained release formulations. In the present work, in situ gel formulation has been developed using poly (lactide-co-glycolide) to deliver an antidiabetic drug-rosiglitazone, that can be given by subcutaneous route. The effect of different vehicles (N-methyl-2-pyrrolidone, triacetin), polymer ... [Show full abstract] concentration and comonomer ratios such as (65:35, 75:25, 85:15) in the polymer on the release of drug from the formulation were studied. The initial burst effect was substantially reduced when the PLG concentration was increased. Out of different comonomer ratios of PLG, the ratio 85:15 showed more sustained release with comparatively less burst effect. The formulations containing triacetin as the solvent showed controlled release of the drug with least burst effect. Good sustained and prolonged release of the drug coupled with biocompatibility characteristics make injectable in situ gel forming implant systems of PLG, a prospective implantable controlled release dosage form to deliver the drug in the therapy of diabetes.