Dear patient there are multiple reason for back pains and in diabetic patient like you can be affected by all the etiology that a non diabetic Pt has. Now since u have sudden onset of pain it is mostly due to muscle spasm.kindly get yourself investigated with radiograph of lumbosacral spine anteroposterior and lateral views to rule out bony abnormalities. I would advise tab diclofenac plus thiocolchicoside combination twice a day along with tab pantocid 40mg twice a day for 5 day's.