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Diabetes mellitus and systemic hypertension affect tens of millions of Americans, and tens of millions more are at risk for these serious diseases that are leading causes of morbidity and mortality.
"Type 2 diabetes and hypertension are silent diseases, and the development of a serious problem, including ocular complications, may be the initial clinical manifestation in some patients," said Dr. Marrelli, clinical associate professor, University of Houston College of Optometry, Houston. "For example, detection of retinopathy by the optometrist may be the finding that leads to a diagnosis of diabetes.
"With awareness of risk factors for these diseases, by routinely measuring blood pressure in all adult patients and by educating patients about healthy lifestyles, optometrists may contribute to early diagnosis and improved prognosis," she said.
The importance of optometrists' involvement in the identification and management of disease in patients with hypertension, diabetes, and those at risk is amplified by statistics on the epidemiology of these diseases. According to the most recent data, diabetes affects about 23.6 million Americans. It ranks as the fifth leading cause of mortality in the United States, and that rank is probably an underestimate considering that diabetes is an underlying cause in many deaths attributed to myocardial infarction and stroke, Dr. Marrelli said.
"One of the most staggering statistics I came across in my research about diabetes is that a male child born in the year 2000 has a 32% lifetime risk for developing diabetes, while a female child born then has a 38% lifetime risk," she said. "These data are a clear demonstration that diabetes is an epidemic, and while type 2 diabetes is generally considered to be an adult-onset disease, it is becoming increasingly prevalent in the adolescent age group due to poor diet and lack of exercise."
The prevalence of hypertension is almost threefold higher than that of diabetes, Dr. Marrelli continued, with the latest statistics estimating that it affects more than 65 million Americans, of whom up to one-third may be unaware of their diagnosis. In addition, another 45 million people are thought to have pre-hypertension, with blood pressure values in the borderline abnormal range.
In patients without an established diagnosis or ocular manifestations suggesting the presence of diabetes or hypertension, review for risk factors will help optometrists identify those who may be affected or are at high risk and also allow them to tailor counseling on lifestyle modification. For type 2 diabetes, the risk factors include age more than 45 years, a positive family history, excessive body weight-especially visceral obesity-physical inactivity, a history of gestational diabetes or delivery of a baby weighing more than 9 lb, and certain ethnicities (for instance, African American, Hispanic).
Hypertension shares many risk factors with diabetes. Its prevalence is increased with age (age more than 55 years in men and more than 65 years in women), by race (African Americans), and in those with a family history of high blood pressure as well as with obesity, physical inactivity, increased alcohol consumption, dyslipidemia, and in persons with diabetes.
"Obesity, hypertension, and diabetes or glucose intolerance are all features of the metabolic syndrome, which will soon overtake smoking as the number one risk factor for cardiovascular disease. All of these conditions interact with each other, and so improving a patient's prognosis is a matter of addressing all comorbidities," Dr. Marrelli said.
The diagnosis of hypertension is based entirely on blood pressure criteria, and blood pressure measurement is an easy test that should be routinely performed in the optometry office on all adult patients. The role of the optometrist is not to make the diagnosis (because that requires more than a single reading) but to identify patients with an elevated value who should be referred to their primary care medical provider for further evaluation.
The American Diabetes Association recommends that all adults be screened for diabetes using a fasting plasma glucose test or, less commonly, an oral glucose tolerance test every 3 years beginning at age 45, or at age 30 for those in a racial risk group and in those with hypertension, body mass index >27, dyslipidemia, or a family history. It is even recommended that children should be screened beginning at age 10 or puberty if they are overweight and have two of the following risk factors: positive family history of type 2 diabetes, racial risk, maternal history of gestational diabetes, hypertension, dyslipidemia, or acanthosis nigricans. Recently, the glycated hemoglobin (HbA1c) test that normally is used in monitoring diabetic control has been advocated as a diagnostic test.
"Optometrists should consider these recommendations and seek to identify whether the patients they are seeing are receiving proper screening," Dr. Marrelli said.
The personal, financial, and societal burdens of diabetes and hypertension are tremendous, but evidence from numerous studies shows addressing modifiable risk factors and controlling blood glucose and blood pressure have a major impact on improving prognosis.
Lifestyle intervention alone-such as increased exercise, modest weight loss, and a healthy diet-may be effective for preventing disease progression in patients with pre-hypertension or pre-diabetes and even for maintaining normal blood glucose and blood pressure in some patients with an established diagnosis of diabetes or hypertension. It is also an essential component in the management of patients who require medical therapy for their disease, however.
Dr. Marrelli urged her colleagues not to leave counseling on behavioral modifications up to the patients' internists and family care physicians.
"We need to be talking to our patients about the importance of appropriate exercise, maintaining an appropriate body weight, controlling blood glucose and blood pressure, smoking cessation, following food pyramid guidelines for eating a healthy diet, and minimizing alcohol consumption," she said.