Type 2 Diabetes Is More Than Hyperglycemia

EDITORIAL

Jennifer B. Marks, MD, FACP, FACE, CDE, Editor

According to Webster’s II New College obese individuals and that is character- ordered glucose metabolism. This con- Dictionary, type 2 diabetes mellitus is ized by hyperglycemia resulting from stellation of conditions is now consid- defined as a “. . . form of diabetes mel- impaired insulin utilization coupled ered a metabolic syndrome that confers litus that typically appears first in with the body’s inability to compensate increased risk for the development of adulthood and is exacerbated by obesi- with increased insulin production.”2 macrovascular complications, in partic- ty and an inactive lifestyle . . . [and] is All true. But these definitions fail to ular, cardiovascular disease (CVD). usually diagnosed by tests that indicate identify that hyperglycemia is only one A wealth of clinical evidence has glucose intolerance. . . .”1 Merriam- part of the picture. Patients with type 2 demonstrated that treating lipid disor- Webster’s Medical Desk Dictionary diabetes typically have a constellation ders and hypertension reduces CVD defines type 2 diabetes mellitus as “a of associated conditions—abnormal risk. While much epidemiological evi- common form of diabetes mellitus that lipid metabolism, hypertension, and dence has linked hyperglycemia and develops especially in adults and . . . in abdominal obesity—in addition to dis- CVD even at glycemic levels that fall

CLINICAL DIABETES • Volume 21, Number 3, 2003 99 EDITORIAL

below the diabetic range, clear evidence lipid control in preventing CVD.5 monly associated features of diabetes— that treatment of hyperglycemia per se Certainly, there are reasons to be lipids, blood pressure, and obesity—to will reduce CVD is lacking. aggressive about the treatment of effectively reduce the risk of CVD in our Still, there are many logical reasons hyperglycemia. Evidence from studies patients. Type 2 diabetes—and CVD— to believe that controlling hyperglycemia such as the Diabetes Control and Com- are more than just hyperglycemia. would reduce macrovascular damage. A plications Trial and the U.K. Prospec- REFERENCES myriad of physiological effects of chron- tive Diabetes Study, which showed that 1Webster’s II New College Dictionary. ic hyperglycemia are not healthy for improved glycemic control can prevent Boston, Mass., Houghton Mifflin, 1999 blood vessels, including excessive pro- the onset or progression of microvascu- 2Merriam-Webster’s Medical Desk Dictionary. Springfield, Mass., Merriam-Webster, duction of advanced glycation end prod- lar complications, has made us aim at Inc., 1996 ucts, activation of protein kinase C iso- lower blood glucose targets. But 3Cooper ME, Bonnet F, Oldfield M, Jandeleit- forms, and sorbitol accumulation.3 All of patients with diabetes die from CVD, Dahm K: Mechanisms of diabetic vasculopathy: these may be atherogenic through a vari- which is the result of the interaction of an overview. Am J Hypertens 14:475–486, 2001 ety of mechanisms. One such mecha- a number of different hemodynamic 4Khaw K-T, Wareham N, Luben R, Bingham S, Oakes S, Welch A, Day N: Glycated hemoglo- nism is the stimulation of cytokines, and metabolic factors. And while I, per- bin, diabetes, and mortality in men in Norfolk which mediate vascular injury both sonally, believe that glycemic control is cohort of European Prospective Investigation of Cancer and Nutrition (EPIC-Norfolk). BMJ through direct toxic effects and indirect- one of them, definitive evidence is 322:15–18, 2001 ly, for example, by increasing plasmino- needed. I refer readers to the feature 5American Diabetes Association: Physicians gen activator inhibitor type 1 activity and article by Carlos Abraira, MD, and rank diabetes as higher risk factor for CVD than 4 smoking. ADA Professional Section Quarterly, C-reactive protein production. William Duckworth, MD, in this issue Summer 2002, p. 4 Despite a lack of hard evidence (p. 107) for a discussion of this subject. 6Abraira C, Duckworth W, McCarren M, indicating a relationship between treat- Results from studies such as the Vet- Emauele N, Arca D, Reda D, Henderson W, for ment of hyperglycemia and reduction in erans Affairs Diabetes Trial6 and the the participants of the VA Cooperative Study of Glycemic Control and Complications in Diabetes CVD, type 2 diabetic patients and their Action to Control Cardiovascular Risk in Mellitus Type 2: Design of the cooperative study health care providers tend to focus on Diabetes (ACCORD) study7 may or may on glycemic control and complications in diabetes mellitus type 2 Veterans Affairs Diabetes glycemic control as paramount. Sixty- not demonstrate that better treatment of Trial. J Diabetes Complications 17(4), July 2003. five percent of primary care physicians hyperglycemia in people with diabetes In press in an American Diabetes Association lowers CVD risk. But regardless of those 7Action to Control Cardiovascular Risk in Diabetes (ACCORD), sponsored by the National poll believed that glycemic control was results, it still will be necessary to Heart, Lung and Blood Institute. www.clinical more effective than blood pressure or aggressively treat all of the other so com- trials.gov

100 Volume 21, Number 3, 2003 • CLINICAL DIABETES