I too am diabetic and have had 4 strokes, so I am very sensitive to your situation, and have developed brines that you can use!
Of course, without saying, trim all visible fat from the loins.
Use a brine of:
1 gal. water
1 cup of Splenda® Brown Sugar Blend
1 cup of Splenda® Sugar
1/3 cup of sea salt
1 well-rounded tablespoon (about 1 ounce) of Cure #1
Stir together until it clears, a couple minutes; it will be in suspension and stay mixed, no need to heat
Of course, use as much as you want, just increase all to the amount of water (if you need 2 gallons, then double the ingredients, etc).
Unless the loin is huge, like 4" or more across, you can just immersion brine it (toss it into the brine, lol) and leave it, refrigerated, for 8-10 days. If huge, you would want to inject the brine in the middle of the loin (when it's 4" or more in diameter so you are curing it from the inside-out as well as the outside-in, then it is now curing only 2" from center to outer edge). There are lots of brining or 'flavor-injector' needles at Walmart or Target that are cheap and you could use one of those; but, they don't broadcast spray the brine as well as a true brining needle, like:
a Morton® brining needle, this one from Butcher-Packer: Morton® Brining Pump
'broadcast spraying' means the needle has a series of holes all through it so the brine shoots out at a 90° angle from the needle and from all sides so it 'pumps' the brine throughout the meat fibers, helping it to cure faster. I use almost ¼ the amount of curing salt needed so it takes a longer soaking in the brine to achieve the same result, aka 8-10 days; you cannot over-brine it like you could if you're using the maximum amount, however, another benefit. Curing Salt is 93.75% plain salt and 6.25% sodium nitrite, so again, you're adding salt, that's why only 1/3 cup of sea salt ('normal' full cure brine is 1 full cup or more) and only 1 tablesppon vs. the maximum amount of 5 tablespoons (3.84 oz) of cure. Your Canadian Bacon is going to have a milder salt taste, possibly too mild for you; but for your father, who is already on a reduced-salt diet, will be more than enough as his tolerance for salt has lowered greatly.
Either way, immerse the meat in a bucket, cover it with enough brine so it floats, then weight it down with a half-full ziploc bag of water and put in the fridge and let it cure. You don't have to stir it or do anything to it, just let it set. While its curing, you're pulling blood and moisture out of the meat and infusing salt and sugar cure into it. The brine will get thicker and bloodier and may have some foaming, this is normal. May even develop a little slime on it or bubbles; it does contain sugars so it is in the early stages of fermenting; nothing to worry about. DO NOT re-use the brine, however; throw it out when it's done.
Once complete, smoke in your smoker to internal of at least 135° for partially cooked or 150° for fully cooked (just partially cooked if you're going to fry it up every time is all that it needs to be). Then, cool and slice and fry up and enjoy! He will look forward to every batch and it will not greatly adversely affect his glucose readings, at least not like commerically product; and this will be much tastier too! But, as always, do a glucose test a half hour - hour after eating just to make sure! (If you have established glucose readings now from standard commercial Canadian Bacon, then mimic those as close as possible so you can test after digesting your own homemade and compare - the proof is in the pudding! Be sure to let us know here, too!).
Good luck and great smoking, hope this helps!