Hi laralady,
1. If his night-time fit is purely diabetes related, i.e. he has no other health issues which could have caused it, then he has had a hypo. This happens when blood sugar falls below a minimum level needed for the brain to function properly. A loss of consciousness and physical spasms are common symptoms.
2. A night time hypo is more likely if basal insulin is administered in a single dose at bedtime. If he was to split his basal dose in two, one before bed and one in the morning, this would be a much smaller risk. He would also probably find his blood sugars more stable throughout the day.
3. Exercise is an important factor too. It has the effect of making insulin work more effectively and can cause blood sugar levels to fall unexpectedly as a result. Exercise is important for his health, but he should be careful to monitor his blood sugar before and after and alter his insulin doses or food if necessary.
4. Hypo's are a possibility at any time of day when you inject insulin. Night time hypo's are probably the biggest risk since he won't be aware of the symptoms as his blood sugar falls during sleep. Splitting the dose is the answer!
All the best,
fergus