Alternative for Swenson condensed milk. I'm diabetic
There are actually many recipes for making your own sugar-free or low-sugar sweetened condensed milk. They generally involve combining non-fat milk or powdered milk and water with a sugar substitute like Splenda. Alternately, if it's sufficiently low in sugar, you can add Splenda or another no-calorie sweetener to evaporated milk.

We don't share recipes here but I encourage you to find one that works for you with your preference of milk product and sugar substitute.