A new study says that nerve damage in the cornea can occur much before type 2 diabetes is diagnosed.
Neuropathy, or nerve injury, is a common and devastating consequence of type 2 diabetes. It can cause pain and numbness in the legs, feet, and hands, as well as muscle and organ disorders, by affecting nerves in different areas of the body.
The loss of nerves in the cornea can result in a variety of disorders ranging from dry eyes to visual loss. In this investigation, it acted as a stand-in for generalised neuropathy.
Dr. Sara Mokhtar of the Department of Internal Medicine at Maastricht University Medical Center in the Netherlands and her colleagues looked at the health of the corneal nerves in people with diabetes, pre-diabetes (when blood sugar levels are higher than normal but not high enough to be called T2D), and people without T2D or pre-diabetes (people with normal glucose metabolism).
The average age of the 3,471 participants (48.4% of whom were men) was 59.4 years. 64.3% of people had neither T2D nor pre-diabetes while 21 % had T2D.
Damage to the ocular nerve fibres increased in proportion to the degree to which glucose metabolism was disrupted. Pre-diabetes caused 8 percent more corneal nerve damage than people with normal glucose metabolism, while T2D caused 8 percent more corneal nerve damage than people with pre-diabetes. When people with T2D were compared to people whose glucose metabolism was normal, those with T2D had 14 percent more nerve damage.
Higher HbA1c (average blood sugar level over several months) and 2-hour post-load glucose (blood sugar level two hours after a meal) levels were also linked to higher degrees of corneal nerve injury.
Additionally, the harm increased as blood sugar levels rose.
Participants with longer durations of diabetes exhibited greater corneal nerve injury.
According to the study’s findings, the degree of corneal nerve fibre damage grew linearly with the severity of glucose metabolism impairment and blood sugar levels.
The move from prediabetes to type 2 diabetes normally takes three to five years, according to other studies, adds Dr. Mokhtar. These findings, from the first study of its sort, imply that type 2 diabetes may not always manifest until high blood sugar levels start to harm corneal nerves.
“Nerve damage in the cornea is relatively easy to measure and provides a window to nerve damage elsewhere in the body. If we could pick up nerve damage early on, we might be able to delay or prevent it and the problems it causes, and so significantly improve quality of life.
“Further research is needed, however, to prove that higher glucose level is the cause of the damage, as well as whether early blood sugar control may delay or prevent it.”
The findings to be presented at the annual meeting of the European Association for the Study of Diabetes in Stockholm, Sweden (19-23 Sept).
Image Credit: Getty
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