I assume your husband doesn't inject insulin, if he is then everything is different.
Do the hypos occur around periods of exercise? Exercise tends to lower blood sugar.
One likely cause is that his sugar spikes after eating and then his body's insulin response overreacts to the situation, making him "crash". Does his sugar go quite high before he goes hypo? If so, then you should try to avoid the sugar spikes, either by eating low-GI or having frequent smaller meals.
However, some people who are not diabetic develop hypoglycaemia (often triggered by exercise); maybe this has happened to him. It can happen if the body's glucagon response is impaired.
If his hypos are always a couple of hours after eating I would guess it's a crash after a sugar spike, but I can't be sure.