This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diabetes, Subject name: Pathology
A 40-year-old diabetic woman complains of flank pain and fever. Her temperature is 38.7degC (103degF), respirations are 25 per minute, and blood pressure is 150/90 mm Hg. Urinalysis reveals pyuria with WBC casts. Which of the following features of diabetes is the most impoant contributing factor in development of flank pain and fever in this patient? 
Select and explain. 
A. Anti-insulin antibodies, B. Glycosylation of hemoglobin, C. Peripheral insulin resistance, D. Hyperglycemia
D: Hyperglycemia
Answer: D: Hyperglycemia 
Explanation: - Flank pain, fever & pyuria are indicative of acute pyelonephritis, a common complication of diabetes. - Glucose in urine provides an enriched culture medium for bacteria to grow. - Patients with autonomic neuropathy often have dystonic bladder that retains urine which fuher increases risk of pyelonephritis. - Pyelonephritis is constant threat for patients with diabetes & necrotizing papillitis may be devastating complication of renal infection. Other choices are not related to renal infection.