This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pancreas, Subject name: Pharmacology
A known case of chronic kidney disease stage 4 is on insulin therapy. What adjustment in insulin dosage is required? 
Select and explain. 
A. Increase dose of insulin, B. Decrease dose of insulin, C. Variable, D. No alteration in dose
B: Decrease dose of insulin
Answer: B: Decrease dose of insulin 
Explanation: Some of the insulin is cleared by the kidneys. No dose adjustment is required if GFR is more than 50 mL/min. If GFR is less than 50 mL/min, then insulin dose should be reduced. As in CKD stage 4 GFR is <15mL/min so the dose of insulin should be decreased.