Unfortunately, because high blood sugar weakens the immune system, diabetes can create a vicious circle where inflammation raises blood sugar which deactivates the immune system components that should fight the inflammation, allowing the inflammation to increase, and further raising blood sugar.
A very common site for inflammation that can have this kind of effect is the gum. Dr. Richard K. Bernstein, author of Dr. Bernstein's Diabetes Solution: The Complete Guide to Achieving Normal Blood Sugars has long preached about the importance of eliminating the infection associated with gum disease.
The usual way dentists approach treating gum disease is to treat it with antibacteria mouthwashes and gum surgeries until, inevitably, the teeth all have to be removed. Dr. Bernstein suggests treating it with a long-term aggressive course of antibiotic therapy. This is controversial because of the side effects of long term antibiotic use, but he reports that this approach is successful and lowers his patients' blood sugars. He doesn't comment on whether it allows them to keep their teeth, which would be worth knowing.
A meta study published in this month's edition of the journal, Diabetes Care reviewed the research on the relationship between periodontal treatment and A1c and concluded that such treatment appeared to lower the A1c. Unfortunately, because this is a meta study, the definition of "periodontal treatment" is different from study to study, which limits its usefulness and keeps the metastudy's finding from being "robust."
You can see that study here:
Effect of Periodontal Treatment on Glycemic Control of Diabetic Patients: A systematic review and meta-analysis. Wijnand J. Teeuw et al. Diabetes Care February 2010 vol. 33 no. 2 421-427. doi: 10.2337/dc09-1378
It is worth noting that other studies have linked the presence of gum disease with the development of heart disease. This association may or may not be independent fact that blood sugars in the "prediabetic range" also raise the risk of heart disease. The incidence of heart disease increases dramatically as blood sugars rise into the "pre-diabetic" range and hit 155 mg/dl (8.6 mmol/L) one hour after glucose challenge. (I blogged about the study documenting that HERE.) It is not known whether eliminating the bacteria associated with gum disease after it has occured lowers the risk of heart disease.
Smoking greatly increases the incidence of gum disease, by damaging the tiny capillaries that should bring immune system cells to the gum where they can fight off the infections. This may have something to do with why smoking increases the risk of heart attack.
Gum disease is only one kind of inflammation that can raise blood sugar. Systemic autoimmune inflammatory conditions like Rheumatoid Arthritis and Lupus can also have an impact on blood sugar and I have received anecdotal reports from people who have found dietary ways of controlling their RA which also lowered their blood sugar.
It is possible that the inflammatory effect of gluten on many people who have forms of celiac disease may explain why the elimination of grains from the diet has such a powerful effect on the blood sugar of some people with diabetes beyond the fact that cutting out grains lowers carbohydrates.
There is some evidence that obesity may be associated with an inflammatory state in the fat cells. You can read a summary of research on this topic HERE.
I am not certain that the obesity is causing this inflammation, however, since I know for a fact that in Type 2 Diabetes, the elevated blood sugar or abnormal level of genetically caused insulin resistance is present long before the individual becomes obese. It is quite possible that in humans the inflammation of fat cells precedes the development of obesity. Inflammation may do this by damaging the receptors the fat cells use to take in the circulating peptides the body uses to regulate fat storage and fat burning.
Another area of the body that is prone to low level inflammation that is very difficult to diagnose and treat is the urinary tract. Because the urine of people with diabetes can be full of glucose which feeds invasive bacteria, people with diabetes are very prone to get urinary tract infections.
Unfortunately, the bacteria that cause these infections form bacterial mats which can make these infections very difficult to eliminate. The antibiotics given for urinary tract infections tend to knock back the bacteria rather than eliminate them and over time repeat antibiotic use can breed drug resistant superbugs.
Even worse, these bacterial mats may keep bacteria bound up and prevent them from showing up in cultures in numbers high enough to provide a diagnosis. This is particularly true when the bacteria have colonized the urethrea.
If you have an ongoing problem with recurring urethral symptoms that don't culture, do not jump to the conclusion that you have a non-infectious condition such as Interstitial Cystitis, until you have tried several long term treatments with powerful antibiotics that are known to reach the urethra. Not all drugs routinely prescribed for urinary tract infection reach the urethra. Macrodantin (nitrofurantoin) does not.
One area where treating inflammation may worsen insulin resistance is heart disease. We know now that statins have a positive effect on the subset of people elevated cardiac-specific C Reactive Protein (CRP), which is an index to inflammation in the blood vessels. This effect appears to have little to do with the fact these drugs lower LDL cholesterol and everything to do with the fact that they appear to decrease inflammation in the blood vessels.
But statins do not appear to lower insulin resistance in humans, though they might do this in rodents. In fact there is some evidence that statins increase insulin resistance in humans. I have blogged about that finding HERE.