Reversing trends: Prediabetes to normoglycemia can lessen microvascular complication risk

Simple regression from prediabetes to normoglycemia can halve patients' future risk of diabetes and lessen their risk of microvascular complications, a new study claims, lending credence to optometry's utility in diabetes care.

Published in the journal Diabetes Care, the analysis described how regression from prediabetes to normal glucose regulation (NGR)— even just once during the Diabetes Prevention Program (DPP) study—was associated with not only reduced incidence of diabetes by 56% over a decade, but also lower prevalence of microvascular disease (MVD), nephropathy and retinopathy due to lower glycemic exposure over time. Such evidence suggests that MVD may be possible even among the prediabetes hemoglobin A1c range and timely, concerted intervention may help stave off those repercussions.

Today, some 30.3 million Americans have diabetes while another 84 million have blood-sugar levels high enough to be considered prediabetic. Of those with prediabetes, 90% aren't even aware of their condition. That alone is troubling, considering prediabetes is a fork in the road where often lifestyle changes—or lack thereof—can make the most difference in whether patients develop diabetes.

But even then, behavior and lifestyle modification might not be enough to hedge against progression. In fact, a post-hoc analysis from the DPP Outcomes Study (DPPOS) found a 31% increased risk for diabetes in people who tried intensive lifestyle modification but did not regress from prediabetes to normoglycemia.

Therefore, the current analysis of the DPPOS went one step further to determine whether regression from prediabetes to normoglycemia would reduce risk for aggregate MVD, as well as if any reduction was due to, or independent of, lower cumulative glycemic exposure.

Per the study, researchers examined the prevalence of aggregate MVD among the DPPOS cohort (2,775 people) year 11 in those who regressed to NGR at least once (vs. never) during the DPP. Overall, about one-third of participants returned to NGR at some point during the DPP and regression to NGR was associated with lower odds of aggregate MVD.

Even among patients with prediabetes, limiting cumulative glycemic exposure remains central to their care. Specifically, researchers observed a 22-30% lower prevalence of aggregate MVD in participants with prediabetes who regressed to normoglycemia, a finding explained by lower A1c over time and lower risk for diabetes.

"Microvascular complications can and do occur in people with prediabetes, and the collective evidence has been deemed sufficient in treatment guidelines for people with prediabetes—largely resembling those for diabetes itself," authors concluded.

"Altogether, the paradigm of treating prediabetes to prevent complications is directly akin to our goals for people with diabetes and argues against the notion of a 'pre' disease."

In fact, researchers posit that prediabetes may simply be an earlier form of diabetes and not just the tipping point as it's often described. To support that claim, researchers note even the landmark UK Prospective Diabetes Study found presence of micro- and macrovascular disease within the recognized A1c range for prediabetes (5.7-6.4%) by the American Diabetes Association.

So, too, researchers noted from the DPPOS data that there may exist different relationships between microvascular subtypes and A1c over time. For instance, nephropathy showed a linear increase over the A1c range over time while retinopathy was slightly more curvilinear, and neuropathy showed no relationship between A1c 4-11%.

"In the era of precision medicine, these findings may have implications for the timing of glucose-lowering intervention based on someone's risk for a particular microvascular disease subtype," authors write.

Such research as the DPP/DPPOS trials, as well as the recent findings described in Diabetes Care, could provide perspective on the conversation of optometry's role in diabetes care moving forward.

Making the case for optometry

Traditionally, optometry's role in diabetes care is often that of triage-detecting the microvascular changes associated with diabetes and transitioning that patient into more comprehensive or advanced care. However, as America's diabetes epidemic continues into yet another decade, doctors of optometry could be called upon to take a more active part in diabetes management and prevention.

"If one looks at the prevalence of diabetes in 1987, compared to the present, one will understand immediately that to meet the current and future public health challenges of the diabetes epidemic, optometry, as a licensed medical profession, must once again reposition itself through expanded clinical services that may necessitate expansion in scope of practice, both horizontally and vertically," announced AOA Immediate Past President Samuel D. Pierce, O.D., in the November/December 2018 edition of AOA Focus.

Pilot research launched in early 2018 found that when doctors of optometry integrated diabetes management strategies-self-monitoring of blood glucose (SMBG) and patient education—into their diabetic care routines, patients with diabetes listened. In fact, these traditionally noncompliant patients were more engaged in SMBG and more likely to test daily, and nearly 20% reconnected to their primary care providers at the urging of their doctor of optometry.

Researchers emphasized the benefit of point-of-care-testing (POCT) in-office that aided these consultations, by incorporating real-time clinical data into individual SMBG education. Michael Duenas, O.D., AOA chief public health officer, noted it's time for optometry to take a greater role in assisting patients' glycemic control, attainment of suitable body-mass index, reduction of cardiovascular risk factors and avoidance of nephropathy.

"Furthermore, optometry must contribute to the early diagnosis and prescribed treatment of type 2 diabetes and prediabetes," Dr. Duenas said in the AOA Focus article.

"To get to this point, it is simply a matter of turning on what is already there: adding laboratory testing or POCT in a way that is consistent with optometry training, patient needs and the patient's extended diabetes care team."

AOA's clinical guidance

Want more information about providing contemporary optometric care for patients with diabetes? The AOA's entirely updated evidence-based clinical practice guideline, Eye Care of the Patient with Diabetes Mellitus, will provide the most current clinical guidance for doctors of optometry involved in diabetes care. 

Read more about optometry's call to action for diabetes care in the November/December 2018 edition of AOA Focus.