Stanford study: Blood sugar responses are individualised, GI diet may be ineffective

Modern health enthusiasts advocate for low-GI diets, emphasizing that stable blood sugar helps reduce the risk of chronic diseases. However, a new study suggests that low-GI diets may be "ineffective" or not an accurate indicator, as blood sugar responses vary from person to person. The study analyzed the blood glucose and insulin sensitivity of 6 "carb-response types," including Rice, Potato, Bread, Pasta, Grape, and Legumes & Berries Type. It found that "Grape Responders" have stable blood sugar and a low risk of developing diabetes. A doctor has proposed 4 ways to monitor daily blood sugar and find a dietary approach that suits your individual response.

A study published in Nature Medicine by Stanford Medicine found that post-meal blood sugar responses are actually "personalized," meaning that GI (glycemic index) values are no longer absolute indicators of healthy eating. The study recruited 55 participants without a history of diabetes. They consumed equal portions of 7 different carbohydrate-rich foods (rice, bread, potatoes, pasta, legumes and berries, and grapes). Using continuous glucose monitors, researchers assessed each person's insulin sensitivity and blood glucose changes. They discovered that postprandial glycemic responses (PPGR) to the same carbohydrate varied significantly between individuals. The participants could be categorized into the following 6 "carb-response types":

1. Rice Responders

• 35% of participants responded most strongly to rice. This group mainly consisted of Asian individuals, indicating a particular sensitivity to high-GI staple foods.

2. Bread Responders

• 24% of participants responded most strongly to bread, a pattern more commonly observed in individuals with high blood pressure.

3. Potato Responders

• A smaller number of people responded significantly to potatoes. Most had insulin resistance and poorer beta-cell function, indicating an increased future risk of diabetes and fatty liver disease.

4. Pasta Responders

• A small number of people had a strong response to pasta. This suggests that even starches considered less digestible are not necessarily gentle on everyone's blood sugar.

5. Grape Responders

• 22% of participants responded most strongly to grapes. These individuals were mostly insulin-sensitive, indicating good metabolism, stable blood sugar, and a low risk of developing diabetes.

6. Legumes & Berries Responders

• Almost no one had a significant response to legumes or mixed berries. These two types of food are ideal carbohydrate sources, providing stable blood sugar responses.

Doctor Teaches 4 Ways to Self-Assess Your Carb Response Type

Physician Dr. Chia-Ming Chang, a specialist in genetics and eugenics, analyzed the study on his personal Facebook page. He noted that if you don't know your carb response type, you can start by observing your daily blood sugar patterns. Through continuous glucose monitoring, self-testing blood sugar after meals, and the following 4 indicators, you can get an initial sense of which carbohydrates you react to most strongly:

1. Feeling particularly tired after eating certain foods
2. Becoming easily irritable or experiencing decreased concentration after meals
3. Having high body fat percentage, concentrated around the abdomen
4. Having a family history of diabetes but not yet diagnosed yourself

Potato Responders Should Pay Attention to Poor Metabolism: 5 Ways to Improve Blood Sugar Response

Using Potato responders as an example, Dr. Chang notes that if you feel drowsy, intensely hungry, or have difficulty concentrating after eating potatoes, you may be a Potato Responder. Potatoes contain resistant starch and theoretically should not spike blood sugar too much. However, if your insulin function is poor, even eating potatoes with side dishes can still cause your blood sugar to rise significantly. Your insulin response may be becoming sluggish, unable to quickly bring blood sugar back to a stable level, indicating signs of insulin resistance and beta-cell stress. High PPGR is also accompanied by higher fasting blood sugar, triglycerides, and free fatty acid concentrations.

Potato Responders can follow these 5 strategies to adjust their diet:

1. Cook potatoes first, then refrigerate them to form resistant starch before eating.
2. Always pair potatoes with high-protein and high-fiber foods, such as tofu and green vegetables.
3. Switch to low-GI staple foods like brown rice, quinoa, or legumes.
4. Perform resistance training 2-3 times per week to improve insulin sensitivity.
5. Use a continuous glucose monitor to observe your own response curves and identify your personal dietary "triggers."

8 Early Symptoms of Diabetes to Watch For

According to the Hong Kong Hospital Authority, there are approximately 700,000 people with diabetes in Hong Kong, accounting for about 10% of the population. This means 1 in every 10 Hongkongers has diabetes. The trend is also affecting younger people, with a 2% prevalence rate among those under 35.

Diabetes is a chronic metabolic disorder. It occurs when insulin secretion is insufficient, or when the body cannot effectively utilize the insulin it produces, causing blood sugar levels to rise. High blood sugar leads to metabolic disorders of fats and proteins and can, over time, damage multiple body systems and organs, including the cardiovascular system, retina, nerves, and kidneys.

Common Early Symptoms of Diabetes:

• Frequent thirst
• Frequent urination
• Feeling hungry
• Unexplained weight loss
• Easy fatigue
• Blurred vision
• Slow-healing wounds
• Skin itching (women may experience genital itching)

According to the Department of Health, diabetes is primarily categorized into two main types:

Type 1 Diabetes (Insulin-Dependent):

• Cause: Destruction of the insulin-producing cells in the pancreas, leading to an inability to produce insulin.
• Risk Factors: Genetics, autoimmune disorders, or environmental factors.

Type 2 Diabetes (Non-Insulin-Dependent):

• Cause: The most common type. Insulin secretion may be normal or only slightly reduced, but the body cannot use the insulin effectively (insulin resistance).
• Risk Factors: Genetics, poor dietary habits, obesity, or lack of physical activity.