A normal fasting blood sugar reading is no guarantee of good health. As cases of "hidden diabetes," in which blood sugar spikes sharply after meals, continue to rise, experts say fasting glucose alone is no longer enough to detect the disease.
One in seven South Korean adults aged 30 or older, or 14.8%, had diabetes as of 2022, according to the Korean Diabetes Association's Diabetes Fact Sheet 2024, released on the 4th. The number of people with the disease reached 5.33 million, and including the 14 million classified as prediabetic, about 20 million people need blood sugar management — close to half of the adult population.
Annual medical spending on type 2 diabetes totals 3.2 trillion won ($2.3 billion), the second highest after hypertension, and has nearly doubled over the past decade since 2015.
Normal Fasting Glucose Is Not Enough — Check Post-Meal Levels and HbA1c Too
The problem is that many cases of diabetes are missed when patients rely on fasting glucose alone. Fasting glucose is measured after at least eight hours without food, and even a reading within the normal range — below 100 mg/dL — can mask postprandial hyperglycemia, a sharp rise in blood sugar after eating.
The Korean Diabetes Association notes that using fasting glucose alone puts the prevalence rate at 14.2%, lower than the 14.8% found when HbA1c readings are also applied. An accurate diagnosis requires a two-hour post-meal glucose test or a glycated hemoglobin (HbA1c) test. HbA1c reflects average blood sugar levels over the previous two to three months, covering the gap that fasting glucose misses.
Experts point to diet and exercise as the core of blood sugar management. On diet, the basic approach is to cut back on foods with a high glycemic index (GI), such as white rice, white bread and snacks, and shift toward brown rice, multigrain staples, legumes and vegetables. Walking for just 10 to 15 minutes after a meal, instead of lying down on the sofa, can reduce the post-meal spike. Combining at least 150 minutes of aerobic exercise a week with strength training helps improve insulin resistance.
Foods recommended for people with diabetes include broccoli, spinach and cabbage, which are rich in dietary fiber that blunts blood sugar spikes; nuts, which contain unsaturated fats; and avocados, which are high in magnesium, a mineral involved in blood sugar regulation.
There are other risks beyond lifestyle habits. Heavy drinking can interfere with glucose production in the liver and trigger hypoglycemia, while smoking raises insulin resistance and makes blood sugar harder to control. Lack of sleep is another factor that pushes blood sugar higher. When sleep falls below six hours, levels of cortisol, a stress hormone, increase and drive glucose up.
Even with a normal fasting glucose reading, people who are obese, have high blood pressure or have a family history of diabetes should get regular HbA1c tests and check their post-meal blood sugar as well.
