Glycaemic Burden and Cognitive Screen-Positive Status in Younger Indian Adults with Long-Standing Type 2 Diabetes: A Cross-Sectional Study with a MoCA Cutoff Sensitivity Analysis in a Lower-Education Population

For decades, doctors have known that diabetes does more than just damage the heart and kidneys; it also quietly erodes the mind. High blood sugar over many years can wear down the brain's wiring, making it harder to remember things, plan ahead, or process information quickly. Because of this link, medical guidelines recommend that older adults, typically those over sixty-five, get their thinking skills checked regularly. However, a large gap remains in this advice. Millions of people develop type 2 diabetes much earlier in life, often in their thirties or forties, and live with the disease for decades before they reach retirement age. Current rules leave these younger adults unmonitored, assuming their minds are safe simply because they are not yet elderly. This leaves a critical question unanswered: does the long-term burden of high blood sugar damage the brains of working-age adults, and if so, how can we tell?

To find the answer, a team of researchers in New Delhi set out to examine the minds of people living with long-standing diabetes who were still in the workforce. They focused on a group of 110 adults, all under the age of sixty, who had been managing type 2 diabetes for at least five years. To understand if their struggles were unique to diabetes, the researchers compared them to 50 healthy people of similar age, gender, and education level who did not have the disease. The team used a standard thinking test called the Montreal Cognitive Assessment, which asks people to draw shapes, recall lists of words, and solve simple puzzles. A score of thirty is perfect, and the test is designed to catch early signs of trouble. The researchers were particularly interested in how the results changed depending on the "passing" score they used, because in populations with less formal schooling, the standard passing score often flags too many healthy people as having problems.

The study revealed a clear and steady pattern: the higher a person's blood sugar levels were, the lower their thinking scores tended to be. This relationship held true regardless of which passing score the researchers chose to use. For every small increase in a person's average blood sugar level, measured by a test called HbA1c, the likelihood of them scoring low on the thinking test increased. This was not a sudden jump but a continuous slide; the worse the blood sugar control, the more likely the brain showed signs of strain. The length of time a person had lived with diabetes also mattered, but only when the researchers used stricter scoring rules. The longer someone had the disease, the more likely they were to show cognitive difficulties, suggesting that the damage accumulates slowly over the years.

Perhaps the most important discovery was about how to use the thinking test itself. The researchers found that the standard rule for passing—scoring twenty-six or higher—was too generous for this specific group. When they applied this standard rule, nearly three-quarters of the healthy control group failed the test, even though they had no diabetes. This meant the test was failing to distinguish between healthy people and those with the disease; it was flagging almost everyone as having a problem. However, when the researchers lowered the passing score to twenty-three, the picture changed dramatically. At this stricter level, only a tiny fraction of the healthy people failed, while a significant portion of the diabetic group still scored below the line. This lower threshold successfully separated the two groups, identifying a specific group of diabetic patients who needed further, more detailed evaluation.

The study also looked at which parts of the brain were most affected. The people with diabetes struggled most with tasks involving abstract thinking, such as finding similarities between different objects, and with delayed memory, where they had to recall a list of words after a short wait. These are the exact areas of the brain that are known to be vulnerable to the effects of high blood sugar and insulin resistance. While the researchers could not prove that high blood sugar caused the decline in this specific snapshot in time, the strong link between sugar levels and test scores suggests that keeping blood sugar under control is vital for protecting the mind, even in younger adults.

Ultimately, this research suggests that the current guidelines for checking the minds of diabetic patients are too late. Waiting until a person turns sixty-five ignores the years of damage that may have already occurred. The study indicates that for younger adults with long-standing diabetes, especially those with less formal education, a lower passing score on cognitive screening tests is necessary to find those who are truly at risk. By using a more appropriate threshold, doctors could identify these patients earlier and refer them for deeper testing, potentially slowing the progression toward more serious memory loss. The work does not offer a cure, but it provides a clearer map for where to look, ensuring that the warning signs of brain decline are not missed in the years before old age.