I eat a lot of plain yogurt. Good stuff is expensive so I looked into getting a yogurt maker making my own.  Turns out it's super easy and you can get a 1 quart yogurt maker on amazon for about twenty bucks.  Apparently you can use a slow cooker if it has a setting that holds the correct temperature.  There are a ton of places online with detailed instructions.

All you do is heat a quart of any kind of milk to about 180 -190 F hold for a few minutes, then let it cool to between 100 and 110f. The heating kills undesirable bacteria and breaks down the milk protein so it will ferment easier.  When it gets below 110F, thoroughly whisk in a couple of tablespoons of live culture yogurt (fresh plain store bought live culture yogurt will work fine) then put it in a covered container and maintain that temperature for about 8 hours or so.   You are basically culturing lactobacillus species and so long as everything is clean before you start it's pretty foolproof.   You can get powdered live yogurt culture online if you want a particular strain.

What you get will be somewhat more tart and runny than commercially packaged plain yogurt but very tasty.  If you want the thick greek style stuff you strain it with a cheesecloth in a colander over a bowl but it's not necessary. Reserve some in a jar and refrigerate and you can use it to culture the next batch.

I'm a believer in the "probiotic" benefits of yogurt insofar as it crowds out bad bacteria and repopulates your gut with benign strains.  It keeps my IBS in check like magic.   Because it's fermented, most of the lactose is broken down so if you're lactose intolerant it shouldn't cause problems.  

In any case, if you're interested, it's extremely easy and you can also make things like sour cream as well.

I make all my own, rather than buy yogurt and introduce it into what I'm making, I buy yogurt starter from the local natural food store, each box is six packets, enough to make six quarts, kept under refrigeration it lasts for a good while.
Pouring the heated milk through a metal strainer after heating seems to make it bit smoother, it eliminates whatever air and foam you've introduced by whisking or stirring while heating.
I also take fresh fruit, cherries peaches strawberries, combined with a reduced simple syrup in the bottom of the container is good too.





ETA  This is the one I use.


https://www.amazon.com/Cuisine-YM100-Automatic-Yogurt-Maker/dp/B001KZM4Y4/ref=sr_1_1?s=kitchen&ie=UTF8&qid=1468726379&sr=1-1&keywords=YM+100






 

I use my sous vide machine and canning jars.

Same steps as above but the water bath is 5 to 6 hrs and done.

I love yogurt, but all the commercial stuff is extremely loaded with sugar, and I'm diabetic.

How's the homemade stuff for sugar? Is sugar a byproduct of the microbes doing their thing, or is it added by the makers afterward?

I stopped making it, but you don't need a yogurt maker.

Put a gallon of whole milk in a pan and heat it to 160-180 degrees and hold it at temp for one hour to denature the proteins.


Cool to about 118 degrees by setting the pan in cold water in your sink, and then stir in some yogurt from the previous batch.


Wrap the pan in a sleeping bag and set somewhere for 10-12 hours.


Drain in a cheesebag for a few hours to about 60-70 percent of starting volume.


You get nearly 3 quarts of the best silky smooth Greek yogurt for the cost of a gallon of milk. If you are not fat-phobic, stir in a cup of cream and have the food of the gods . . .

There is very little sugar in plain yogurt.  .This is the kind of stuff you want to be eating if you are diabetic.  It is not sweet.  The bacteria ferments the lactose (milk sugar) into lactic acid which is what makes it nice and tart.  The sugar content is just the residual natural lactose that remained unfermented.  Some types of bacteria ferment sugars in things like grape juice and barley malt into alcohol which is proof God loves us and wants us to be happy.

Read the ingredients.  Store bought flavored yogurt had loads of added sugars; its basically candy.  Plain live culture yogurt is high in protein and calcium.    I put it over a low sugar granola in the morning to get fiber.   Try adding some nice ripe berries or honey to it if you want it sweeter.   Or go middle eastern, drizzle with olive oil and paprika and eat it with pita bread.  I like it plain.  

There is nothing really wrong with the plain store bought live culture yogurt but the cultures will not be as active due to being refrigerated for so long.

I just use a slow cooker. After the initial heating, then cooling to a safe temp for adding the starter, I just wrap it in a towel and stick it in the oven with just the light turned on, and leave it overnight.

Easy peazy.

And if for some reason your yogurt doesn't come together, you can rescue it by making ricotta.