Ming, you are trying to do your best for your husband but I think that you are trying to follow all sorts of advice, some probably good , a lot definitely controversial and some (in my opinion) very dubious. Everyday someone is making a different suggestion. I don't know how you can follow it all.
Making rapid drastic changes overnight is not usually thought to be a good thing, These changes are very often short term leading to 'cheating' because the person feels deprived . Moreover, most 'experts' do not advocate very rapid weight loss, unless overseen by a doctor, particularly for people with existing medical conditions.
I agree totally with Romala, ( edit: and others, I was slow debating how to answer) our health and therefore eating to be healthy encompasses a lot more than diabetes. I feel that you should look again at sources of general advice such as the British Heart foundation.The advice from diabetes UK (the charity) did unfortunately contain the words to eat 'plenty of starchy carbs at each meal'. (and if you delve far enough the eatwell plate is still there). This has now been partly revised to say eat some at each meal and to favour those with a lower GI. The general guidance (10 steps to healthy eating ) is in line with other European countries. They aren't all trying to kill people off,nor force them onto insulin or expensive medications either (insulins pens are far too expensive)
As to specific advice such as possible problems with medication, he should discuss this with his doctor... no-one on here (Including any medical professionals) has access to his medical history so cannot give competent advice. It may be that he also needs to get advice on his constipation problem , with the doctor, particulalry as it seems to be causing a large amount of discomfort and bleeding.
http://www.bbc.co.uk/health/conditions/constipation1.shtml
You may be encouraged by others to carry on this diet. It should be your husband's decision. If you do decide to continue , please try to introduce far more veg and fruit (most low carbers accept some berries). Fibre is a very important part of any diet.