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Elevated haemoglobin A1C (HbA1C) levels correlate strongly with persistent clinically significant macular oedema (CSME) in patients with type II diabetes, report Wilmer Eye Institute researchers. "Awareness and understanding of the HbA1C values in patients with persistent CSME may help ophthalmologists to provide better management of CSME," notes Quan Dong Nguyen MD, MSc.Dr. Nguyen and colleagues reviewed the medical records of all type II diabetics who received eye care from a single retina specialist for persistent CSME in one or both eyes between August 2001 and August 2002, and who have had their HbA1C measured at the Johns Hopkins Medical Institutions within 3 months of the time at which persistent CSME was detected. The initial review identified 50 patients, ranging in age from 43 to 82 years (mean 65 years). Nineteen patients (38%) had unilateral persistent CSME and 31 patients (62%) had bilateral CSME. The average number of focal laser photocoagulation treatments among all eyes was 3.5. HbA1C values ranged from 5.3% to 15.6% (mean 8.9%). Forty-one patients (82%) had HbA1C greater than 7.0%, and 36 patients (72%) had HbA1C greater than 7.5%, within three months of the time of their persistent CSME. Among the 19 patients with unilateral CSME, mean HbA1C was 8.2%. Among the 31 patients with bilateral CSME, mean HbA1C was 9.2%. The normal range of HbA1C values in non-diabetics, established at Johns Hopkins laboratories, is 4.5% to 6.1%. The United Kingdom Prospective Diabetes Study showed that intensive control of blood glucose (reducing HbA1C to 7.0%) was associated with a decrease in microvascular complications in patients with type II diabetes. Dr. Nguyen believes that, in addition to other forms of ophthalmic treatments, management of persistent CSME may require tighter glucose control in the diabetics. "We are looking at the correlation between persistent CSME and HbA1C levels," he told EuroTimes. He noted that patients with poorly controlled diabetes are at risk of developing diabetic retinopathy, including macular oedema. A patient with diabetes and eye disease is often followed by a primary care physician as well as by an ophthalmologist. He voiced concern about inadequate communication between the two teams of health care providers regarding the degree at which the diabetes should be controlled. "Ophthalmologists often suggest to the patients to go and discuss with their primary care doctors regarding blood sugar control. As the primary care physicians try to control the patient, they may set a certain level of haemoglobin A1C, which may be appropriate to decrease the risk for diabetic nephropathy or neuropathy, but which may not be appropriate to prevent further progression of the retinopathy, including diabetic macular oedema. However, as ophthalmologists, we know that there are many patients with diabetes who otherwise have control of their neuropathy or nephropathy, yet have persistent retinopathy. Therefore, even though the primary care physician may think that the patients are under control (often they are not able to examine the retinopathy), we need to determine if the diabetes is really under control in terms of eye disease according to the HbA1C targeted by the primary care physicians," Dr Nguyen told EuroTimes. "My message is that as ophthalmologists, we should also be aware of the values of haemoglobin A1C because it is our goal and responsibility to communicate to the primary care physicians the haemoglobin A1C level at which persistent macular oedema is often detected. I think by providing our primary care colleagues with a specific target associated with CSME, they can help us to better manage our patients," Dr. Nguyen added. Lucy H. Young MD, PhD of the Massachusetts Eye & Ear Infirmary notes that the design of Nguyen's study has certain limitations, such as its retrospective design. "I don't think it's appropriate to compare patients with unilateral CSME with bilateral CSME without a control group without persistent macular oedema. It is important to prospectively follow hundreds of patients and then make comparisons of those with persistent macular oedema and those without macular oedema," Dr. Young told EuroTimes. Dr. Nguyen agreed that Dr. Young's remark is a well-considered point that has been taken into account, noting that his original presentation was preliminary and the ongoing study now includes many more patients. "We are also looking at diabetic patients without persistent macular oedema; the HbA1C values are indeed lower in this population. We will report these results along with the results on diabetic patients with persistent oedema in the manuscript. We also plan to do a prospective study in the future." Dr. Nguyen presented his initial results at the 2003 meeting of the Association for Research in Vision and Ophthalmology. Dr. Nguyen's research on diabetic macular oedema is supported by a K23 Career Development Award from the National Eye Institute of the United States' National Institutes of Health.Quan Dong Nguyen, MD, MSc Lucy H. Young MD, PhD |
