The most important thing is to find where you might be ingesting or otherwise getting exposed to chemicals. Occupational exposures, hobbies, living near an agricultural area or golf courses or factories, etc. are important to think about. Don't eat processed foods and beverages, nonorganic foods (especially animal foods - they have much higher concentrations of chemical toxins than plants do), personal care products and detergents, avoid eating/drinking from plastic containers, don't eat canned foods (they have plastic liners or are lined with resins) or use cookware with a nonstick coating. A lot of chemicals are taken in through manufactured beverages or drinking from plastic containers, and people don't tend to think about those exposures. The best way to clear chemicals overall is through heat-induced sweating. Sauna (either IR or ambient heat is fine) is the most effective method, then hot Epsom salt baths (the Mg sulfate binds chemicals in the water and keeps them from reabsorbing back through your skin). Exercise-induced sweating is good too. I suggest taking 1-2 tsp extra sea salt and water those days, as well as taking at least 1200mg NAC and 2,000mg vitamin C about half an hour before getting in the sauna. Alpha lipoic acid, magnesium, glycine, maybe other supplements might help with that level of detox too. If you want to assess for insulin resistance fasting levels are not helpful at all until it's WAY too late. You should drink some juice with about 50-75g of sugar total, then go to the lab and have blood drawn 30-45 minutes later to check glucose and insulin levels. That's how you can tell, you have to challenge yourself with a load of sugar and see how much insulin your body produces in an effort to control your blood glucose level.