Hi,
When i used lantus i was told then when changing basal insulins that any change should be left for at least 3 days to see the effects of any change.
You shouldn't change his basal insulin because he's slightly high one night.
The whole idea that the basal insulin is meant to control the changes in BG's that your body naturally causes and to have a background as a normal pancreas does.
The bolus insulin is solely to cover what you eat and bring any highs down to a normal level.
If it seems he's having highs or lows that seem to be around the same time of day then it could be likely the basal needs altering.
Depending on what bolus insulin you use and how long it takes to wear off can indicate the basal insulin needs tweaking, by this i mean if he went low 5/6 hours after a meal, and your bolus insulin only has a life of 3-4 hours this would indicate that it's the basal insulin thats causing the hypo.
Hopefully you use a diary so this is a very important tool in spotting any trends over the past few days that would indicate changes being needed.
If he is slightly high after a meal, make sure you know the carbs were counted accurately and that his ratio for insulin is accurate.
Hope this helps and makes sense