Like "You may be eating fewer carbs and getting more exercise than you would when at home. I would first try to adjust either lunch or dinner time carb to insulin ratio from 1:10 to 1:12 and see if that makes any difference. When do you take your Lantus dose...morning or evening? Although Lantus provides a 24-hour mostly steady dosage of basal insulin, it does have a slight peak right after injection. Any adjustments without your doctor's input should be made tiny bit by tiny bit. I would also counsel on not changing both the basal (Lantus) and bolus (carb to insulin ratios) at the same time. Wishing you well."