Hi ! Good morning. I am Dr Shareef answering your query. There has to be a source of infection to get persistent fever, and in your case, with the history you have narrated of evening rise of temperature specially with a known history of diabetes, the most likely source looks to be a urinary tract infection which could also give rise to both your lower back and abdominal pain. If I were your doctor, I would advise you to monitor your blood sugar level very closely, go for a urine routine/microscopic/culture and sensitivity test so that appropriate antibiotic could be instituted if need be, and possibly an ultrasound abdomen. I would also advise you for a fever profile like a CBC, ESR, Typhi dot, and blood for MP, with a peripheral smear as well. The management in your case would depend on the results of a physical examination and reports of the related investigations. Till that you can go for an over the counter antipyretic like paracetamol, and an anti spasmodic for the abdominal pain along with a diabetic diet. I hope this information would help you in discussing with your family physician/treating doctor in further management of your problem. Please do not hesitate to ask in case of any further doubts. Thanks for choosing health care magic to clear doubts on your health problems. Wishing you an early recovery. Dr Shareef.