The answer is both: yes and no. Yes, because he's in acute stress and any stress tends to increase blood sugar levels and it increases resistance to insulin
further. This requires futher titration of insulin doses. So just take help of your Diabetes
Nurse educator or Diabetologist
for adjusting his insulin doses as running with very high sugars will delay progress of any other illness in good direction. No, because lymphoma
as such does not increase or decrease blood sugars directly. But the stress must be understood and action to be taken faster. All the best.