What ophthalmologists need to know about diabetes

October 1, 2016

The increasing prevalence of diabetes, which implies a rise in the number of cases of diabetic retinopathy, suggests that ophthalmologists need to ensure their knowledge of this disease is up-to-date. Hazy memories of a long-ago medical school lecture from an endocrinologist or the guidelines in an outdated textbook are inadequate given changes in the understanding of the pathogenesis, diagnosis, and especially the treatment of diabetes.

Reviewed by Mandeep Brar, MD

Glendale, AZ: Diabetes is extremely common in the United States, with the current prevalence approaching 10% of the population and forecasts predicting that it could affect up to one third of adults in the country by 2050. Since retinopathy develops in about 21% of diabetics, the implications of the growing problem of diabetes and its comorbidities are highly relevant to ophthalmologists. Yet many have gaps in their knowledge about diabetes mellitus because of recent and rapid advances in treatment guidelines, according to Mandeep Brar, MD, an endocrinologist in private practice in Glendale, AZ.

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A frequent educational speaker for audiences of ophthalmologists, Dr. Brar has gained insight from questions posed during these presentations, highlighting the need for comprehensive review of updated guidelines, arming them to more completely evaluate this systemic metabolic disease and better manage patients who may be at risk of developing or have developed diabetic retinopathy or diabetic macular edema.

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Ophthalmologists don’t need to rival endocrinologists in their understanding of diabetes, Dr. Brar emphasized, but experience has shown her that many are eager to update their knowledge and would like to participate in a complete discussion. There is also an increased pressure to be able to answer more questions from patients, who themselves are more involved in their disease management.

“Ophthalmologists need a birds’ eye view [of diabetes],” Dr. Brar said. “They need to know what the landscape looks like at this moment, and the landscape has definitely changed since many of them have been in medical school.”

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One common misunderstanding concerns the distinction between types of disease. “Many ophthalmologists have the misconception that type 1 is still considered juvenile onset and that type 2 is only confined to onset in adulthood. We don’t define it that way anymore,” Dr. Brar said. “I have seen an 8-year-old with type 2 diabetes. I have diagnosed people in their 60s with type 1 diabetes new onset.”

Type 1, type 2 diabetes

Briefly, patients with type 1 diabetes have markedly decreased insulin production that is insufficient to support utilization of glucose as a primary source of energy; although the exact mechanism of beta-cell destruction is not completely understood, data suggest their immune system malfunctions, attacking and destroying cells that make insulin. There may also be some environmental triggers to this process. Type 2 diabetes mellitus, which is far more common, affecting about 95% of all people diagnosed with diabetes, is a complex process of eight known possible defects known as the “ominous octet.” One of the first defects is termed insulin resistance. While the pancreas can initially produce extra insulin to make up for the deficit, over time production is insufficient to maintain normal glucose levels in the context of other metabolic changes.

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Ophthalmologists also should become familiar with the most current diagnostic guidelines for diabetes. “A lot of people don’t know that we’ve tightened up on A1C ranges in regard to what is considered normal, what’s prediabetic, and what A1c falls in the diabetic range,” Dr. Brar said. When using hemoglobin A1C levels (Hb A1c) for diagnosis, diabetes mellitus is diagnosed at an A1C of ≥ 6.5%, normal is considered less than 5.7%, and prediabetes falls within the range of 5.7% to 6.4%. Diagnosis of diabetes mellitus can also be made based on two fasting glucose levels of > 126 mg/dL.

If a patient has diabetes mellitus, ophthalmologists should ask about their most recent A1c levels at every visit and discuss the risks of development and progression of retinopathy along the spectrum of disease. They should also reiterate the association of this complication with A1c levels that are not at goal, which for most people is generally considered < 7%.

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This conversation is also an opportunity to encourage patients who are not at goal and provide positive feedback to those who are well controlled with their current management, as well as to review treatment options. “People with diabetes mellitus often feel encouraged when their primary care provider and specialists communicate independently with each other, providing the impression of comprehensive care; therefore, interprovider communication is ideal, including requesting and sharing pertinent lab results,” Dr. Brar said.

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A solid grasp on Hb A1c and blood glucose goals, or familiarity with reliable resources to which patients can be referred-such as the American Diabetes Association-is vital. Anecdotally, it has been noted that patients will often ask their eye care providers for specific recommendations on appropriate glucose levels at various times of the day, driven by the fear of developing significant visual impairment. In these instances, an answer that conflicts with recommendations from their primary care provider (PCP) or endocrinologist-or an “I don’t know”-could be confusing to the patient, resulting in loss of motivation, Dr. Brar said.

Treatment options

The ophthalmologist’s scope of knowledge should also extend to the most common treatment options. “We’ve had an explosion in the diabetes armamentarium in the last 5 to 10 years,” Dr. Brar said. “We have injectable medicines that are not insulin; we have newer oral agents that have a greater Hb A1c lowering benefit. These options provide better glucose control for certain patients and without causing significant weight gain.”

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Ophthalmologists also may need better information to respond to challenges such as people with diabetes who have worsening blood glucose control despite being compliant with treatment recommendations. This situation requires a detailed metabolic conversation, according to Dr. Brar, and is not simply a matter of advising patients to watch their weight, eat less, and take medicine. “Though these recommendations are made with the best intentions, they can be perceived as negative by those living with this condition,” she added.

Dr. Brar suggests that ophthalmologists become familiar with the “ominous octet” and the use of multiple drugs to treat them (http://care.diabetesjournals.org/content/36/Supplement_2/S127).

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Managing diabetes mellitus when considering the core defects of the ominous octet typically involves multiple healthcare providers, including endocrinologists, PCPs, registered dietitians, certified diabetes educators, exercise physiologists, and in certain instances, bariatric surgeons. Taking part in this collaboration could both enhance ophthalmologists’ understanding of diabetes and improve their ability to manage patients at risk of diabetes-related ocular complications. “We need to circle all the providers around these patients,” Dr. Brar said.     

Inter-provider communication including all specialists and especially communication with patients is also vital to optimizing outcomes, Dr. Brar added. She recommends that ophthalmologists routinely provide patients with a brief written summary of findings from their eye exam and send both this summary and follow-up plans-without using abbreviations-to the referring physician.

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“It can be time intensive sharing clinic notes when we’re not in the same health system or in the same practice, but keepingin mind that communicating with each other about the lives that we’re taking responsibility for is a vital requirement of being a sub-specialist,” she said.

 

Mandeep Brar, MD

E: mandeepbrarmd@gmail.com

Dr. Brar has had a financial agreement or affiliation during the past year with Janssen Pharmaceutical and Regeneron Pharmaceuticals.