Long standing diabetes causes diabetic nephropathy. Diabetic nephropathy causes loss of protein from kidney (proteinuria), high blood pressure and chronic renal renal failure leading to elevation of serum creatinine. Serum creatinine is a marker of kidney function. Serum creatinine 3.38 is quite high and is mostly probably due to diabetic nephropathy. Kidney biopsy is needed for pathological diagnosis of diabetic nephropathy and other possible causes of elevated serum creatinine. It is done under ultrasound or CT scan guided needle. It is a relatively safe procedure if done by an experienced person. Complications in diabetic patient may kidney bleeding and infection. But incidence is low if done carefully under ultrasound of CT scan guide needle. Other tests are also available for diagnosis of diabetic nephropathy. Advice 1. Investigations a. Kidney biopsy under CT scan guided needle b. R/E of urine c. Serum total protein d. Serum sodium and potassium e. Blood urea f. Hb% If you have already undergone above tests then there is no need to repeat these tests unless suggested by your nephrologist 2. Consume less protein such as eggs, meat, milk and cheese as high protein diet aggravates diabetic nephropathy 3. Regularly measure your blood pressure 4. Avoid non-steroidal pain killers 5. Regularly take anti-diabetic medicines 6. Always be in touch with your nephrologist I hope this information will help you. I will be happy if you ask another question Thanks