resistance syndrome,” present with several disorders of with type 2 DM. ⁷ After adjusting for other common risk
metabolism, including obesity, hypertension and hyper- factors, it was found that patients with severe periodontal
lipidemia. This syndrome may raise the risk for diabe- disease had a death rate from ischemic heart disease 2. 3
tes and cardiovascular events. ²⁶ A 2-year study of 750 times higher, and a death rate from diabetic nephropathy
patients showed that subjects with metabolic syndrome 8. 5 times higher, than patients with mild, moderate, or
were > 2. 5 times more likely to suffer from stroke, chest no periodontal disease. These findings parallel data from
pains, MI, or heart failure, ⁴³ but questions remain as to several studies suggesting that periodontal disease may
whether this indeed constitutes a true syndrome. ⁴⁴ It be a significant independent risk factor for atherosclero-
is not clear whether metabolic syndrome represents a sis-mediated events such as MI and stroke. ^48-50
greater risk for CVD than any of its component parts, all
of which require treatment. The best evidence for evaluating the influence of periodon-
tal disease on metabolic status comes from intervention

Short of overt diabetes lie the pre-diabetic conditions trials evaluating the effects of periodontal treatment on known as impaired fasting glucose (IFG) and impaired glycemic control. These studies are heterogeneous, and it glucose tolerance (IGT), which together affect over 40 is important to examine them in light of their limitations, million Americans. ^{15, 45} Insulin resistance underlies both including small sample sizes, mixing of type 1 and type conditions, with endogenous insulin secretion being rela- 2 DM patients, confounders such as smoking and body tively normal. Patients with IFG are hyperglycemic during mass index, and varying methods of assessing glycemic periods of fasting, with serum glucose levels returning to control. Nevertheless, the studies suggest that periodon-normal after eating. Those with IGT become hyperglyce- tal therapy may have a positive effect on glycemic con-mic after glucose intake, but are otherwise normoglyce- trol in DM. More than 45 years ago, periodontal therapy mic. Both conditions are significant risk factors for future consisting of systemic antibiotics, extraction of hopeless development of type 2 DM, and IGT has also been identi- teeth, scaling and root planing, and limited gingivectomy fied as a risk factor for MI and stroke. ⁴⁶ was shown to reduce the insulin requirements of subjects with type 1 DM. ⁵¹ These results have been corroborat-

Periodontal Disease: Potential to Impact Metabolic ed in a prospective fashion more recently. ⁵² Scaling and Control of Diabetes Mellitus root planing alone have also been shown to significantly As noted earlier, acute infections may increase insulin improve glycemic control in patients with type 2 DM,^53,54 resistance and thereby reduce metabolic control in DM. although other studies have shown improved periodon-Periodontal diseases have the potential to cause a chron- tal conditions but no improvement in glycemic control in ic systemic inflammatory state, ²⁰ and chronic gram-nega- both type 1 and 2 DM patients.^55,56 Several studies have tive periodontal infections increase insulin resistance and demonstrated that scaling and root planing in combina-negatively impact glycemic control. ⁴⁷ In a 2-year longitu- tion with systemic tetracycline antibiotics, most notably dinal study of type 2 DM subjects, patients with severe doxycycline, improve glycemic control in type 1 and type periodontitis were at 6 times greater risk for worsening 2 DM patients.^57-59 Tetracyclines are increasingly used as of glycemic control over time than patients without peri- an adjunct to mechanical treatment of periodontal disease odontitis, a finding attributed to increased insulin resis- in DM patients because they reduce production of matrix tance. ⁵ metalloproteinases, in particular the enzyme collagenase,

which is known to be produced to a greater degree in

Additional evidence for an association between peri- DM patients.⁶⁰ In these studies, clinically and statistically odontal disease and metabolic control of diabetes comes significant decreases in glycated hemoglobin (HbA1c) from studies evaluating other diabetic complications. In from baseline paralleled a reduction in periodontal ina case-control study over a period of 11 years, 82% of flammation. The best results were seen in patients with patients with diabetes and severe periodontitis had 1 or the poorest diabetic control and with the most advanced more macrovascular complications, such as angina, MI, periodontitis. However, this has not been replicated in all heart failure, transient ischemic attack, and stroke. ⁶ Only studies, and recently a study in patients with poorly con- 21% of DM patients without periodontitis had macrovas- trolled type 2 DM showed only a nonsignificant reduction cular complications. A more recent prospective longitudi- in glycemic control, although periodontal parameters im-nal trial of 628 patents examined the effect of periodontal proved significantly.⁶¹ disease on overall as well as CVD mortality in patients