I'm a caregiver to my live-in partner. He had a stroke, is diabetic that is controlled by medication and diet. He will not drink or eat his foods that need sweetener unless I add 3 to 4 packets. He use to only ask for 1 but now is up to 3 and sometimes demands 4 in his coffee and oatmeal. This seems like too much artificial sweetener. Any advice on side effects since he already had a stroke a year ago.
Good reading on this subject are the "Zone" books by Barry Sears.
Often the very things we crave are the most damaging because we have become addicted to them. We cease to get relief or satisfaction, and thus the craving for more and more, like nicotine or alcohol. It sounds like your partner is addicted not so much to the sweetness, but has developed a dependency on the chemical compounds in artificial sweeteners.
If he is not suffering from dementia perhaps you could reason with him about the damage done by such substances and seek an alternative. I'm not conversant with natural sweeteners that diabetics are able to use, but there must be a wealth of information on the Internet. Long ago they used to tout tupelo honey, but I don't know if that is still considered safe for diabetics.
Regardless of what you use---and this goes for non-diabetics as well---human beings were never meant to consume the amount of sugar that is part of the typical modern diet.