Introduction.
Many people think of diabetes as a disease caused by eating too much sweet food.
In reality, however, diabetes is a disease caused by a combination of multiple factors, including lifestyle, body constitution, hormonal balance, and aging.
This article provides a clear medical explanation of the underlying causes of diabetes and why it is increasing in our society.
1. what is diabetes mellitus - a decrease in the ability to lower blood sugar
When we eat, carbohydrates (sugars) are broken down into "glucose" and enter the bloodstream.
At this time, the hormone insulin is responsible for lowering blood glucose levels.
Diabetes mellitus is a condition in which this insulin does not function adequately and blood glucose levels become chronically high.
There are two main types of diabetes
| type | Main Causes | Time of onset |
| type 1 diabetes mellitus | Pancreatic beta cells that make insulin are destroyed and cannot secrete it | Young onset is common |
| type 2 diabetes mellitus | Decreased insulin secretion + insulin resistance | More common in middle-aged and older people |
About 95% of the Japanese population has Type 2 diabetes. The following explanation focuses on the causes of type 2 diabetes.
2. main cause (1): poor insulin response (insulin resistance)
The main cause of diabetes is "insulin ineffectiveness".
In other words, insulin is being secreted but the muscles and liver are not responding.
Causal Factors
- Accumulation of visceral fat: fat cells secrete inflammatory substances (TNF-α, IL-6, etc.) that interfere with insulin action
- Lack of exercise: reduced opportunity for muscles to take up sugar
- High fat diet and excessive carbohydrates: excess energy and fat deposits in the liver (MASLD)
- Stress and lack of sleep: blood glucose levels remain high due to elevated cortisol
Japanese people, in particular, have less muscle mass than Westerners and are more prone to insulin resistance.
3. main cause 2: decreased insulin secretion
Insulin secretion from the pancreas is essential for processing sugar.
However, if too much sugar or fat is consumed continuously, the pancreas is always in full operation and the beta cells become exhausted.
If this continues, insulin secretion itself will eventually decline and blood glucose control will fail.
- Early stage: Insulin is being produced but not working (resistance)
- Medium-term: Ineffective and secretion decreases.
- End stage: Insulin injections are required.
“Exhaustion” of insulin secretion may be reversible with early lifestyle modifications.
4. major cause ③: heredity and constitution
Diabetes is also related to genetic predisposition.
It has been reported that the risk of developing diabetes is two to three times higher if there is a family member with diabetes.
Especially Japanese more than Westerners:
- Low insulin secretory capacity
- You don't have to be obese to develop diabetes.
For this reason, it is not always the case that "it is not fat, so it is okay.
5. major cause 4: lifestyle and environment
(1) Changes in dietary habits
- High-sugar, high-fat, high-calorie diet
- Disrupted mealtimes, nighttime eating, snacking
Eating late at night, in particular, can easily raise blood sugar and promote fatty liver.
(2) Lack of exercise
Low number of steps per day, mainly at desk, reduced exercise for commuting and housework, etc.
(3) Stress and sleep
Chronic stress stimulates the sympathetic nervous system and raises blood glucose levels through hormones such as cortisol and adrenaline.
(4) Aging
Aging reduces muscle mass and the ability to store glucose.
6. why diabetes is increasing in modern society
- Increase in high-calorie diets, eating out, and eating at convenience stores
- Lifestyle of not walking or moving
- Sleep deprived, stressful society
- Aging population due to increased life expectancy
Especially after the age of 40, the combination of "obesity + lack of exercise + stress" causes a sharp increase in diabetes.
7. evaluation and treatment at Ikejiri-Ohashi Sera Clinic
We evaluate the cause of diabetes "from the entire body condition, not just blood glucose levels.
examination
- Blood glucose, HbA1c, insulin resistance (HOMA-IR)
- Fatty liver (MASLD), visceral fat mass
- Vascular evaluation with fundus, ABI, carotid echocardiography, and Holter ECG
medical treatment
- Dietary guidance (locavore) + physician supervised exercise therapy
- Weight and fat control through medical dieting
- Optimization of drug therapy by a diabetes specialist
We view diabetes not as a "numerical disease" but as a "disease that requires a review of one's entire lifestyle," and aim to build a body that will prevent recurrence.
summary
- Diabetes mellitus is mainly caused by "insulin ineffectiveness" and "reduced secretion".
- Visceral fat, lack of exercise, stress, and aging drive the onset of the disease.
- Japanese people are genetically weak in insulin secretion, so be careful even if you are not obese.
- At Ikejiri-Ohashi Sera Clinic, we analyze the causes of diabetes from many angles and provide treatment based on the four pillars of examination, exercise, diet, and medication.
References
- The Japan Diabetes Society. Diabetes Care Guide 2024-2025.
- DeFronzo RA. Pathogenesis of type 2 diabetes mellitus. Med Clin North Am. 2004.
- American Diabetes Association. Standards of Care in Diabetes 2024.
- Hotamisligil GS. Inflammation and metabolic disorders.
Diabetes Series - Related Article List
1. Know the basics of diabetes
- What is Diabetes - Why does blood sugar rise? Causes and Mechanisms Explained
Introduces the root causes of diabetes, including "insulin resistance," "heredity," and "lifestyle," which are all related to the development of diabetes, in an easy-to-understand manner. - Early Symptoms of Diabetes - Don't Miss the Early Detection Signs
Early signs that are difficult to recognize, such as thirst, polyuria, and weight loss, are carefully explained. - Diagnostic criteria for diabetes - Difference between HbA1c, blood glucose and OGTT and latest criteria
It summarizes the numerical values used for diagnosis and the key points of the recently revised diagnostic criteria. - Diabetes Testing - Comprehensive evaluation of blood, urine, and even complications
Introduction to the comprehensive examination system available at the Ikejiri-Ohashi Sera Clinic, including fundus examination, ABI, and carotid artery echocardiography.
2. Treatment and lifestyle modification
- Diabetes Treatment - Protecting Blood Sugar and Blood Vessels with Diet, Exercise, and Medication
Explains treatment strategies to "prevent complications" rather than "lower the numbers. - Diabetes Diet - Control Blood Sugar Effortlessly with Locavore
A practical diet that emphasizes how to eat, not what not to eat. - Diabetes and Exercise - Muscle is Medicine! The Science of Aerobic x Muscle Training
The benefits of exercise to directly lower blood sugar and how to create an easy to follow exercise routine. - Drug Therapy for Diabetes Mellitus - Latest Treatment Policies and Multi-Drug Approaches
The characteristics of DPP-4 inhibitors, SGLT2 inhibitors, and GLP-1 agonists are compared, and the latest treatment trends are presented.
3. To prevent complications
- Complications of diabetes - Complication measures to remember with "shimeji" and "enoki" mushrooms
The six major complications of neuropathy, retinopathy, nephropathy, gangrene, stroke, and cardiac disease are explained together. - Neuropathy due to diabetes - Mechanisms and countermeasures for numbness and pain in hands and feet
Early signs of peripheral neuropathy and ways to improve life that should be done early. - Diabetes and Renal Dysfunction - Importance of Urine Albumin Testing and Habits to Protect
Practical approaches to reduce the burden on the kidneys and prevent dialysis. - Diabetes and Eye Disease - Causes of Blurred Vision and Early Detection of Retinopathy
Explains how fundus camera examinations work and the risks of neglect.
4. Prevention and early intervention
- Prevention of Diabetes - Reduce blood sugar waves and make your body less prone to diabetes.
Introduces diet, exercise, and sleep regimens to "get in shape before it happens," rather than "fix it after it happens. - Characteristics and constitution of people prone to diabetes - Self-check that you can do now
Early intervention is recommended by sorting out the risk of developing the disease, including heredity, fatty liver, and lack of exercise.
5. Our features and support system
- Lifestyle-related disease treatment at Ikejiri-Ohashi Sera Clinic - Cross-cutting management of diabetes, MASLD, hypertension and dyslipidemia
Includes a comprehensive evaluation system including physician supervised exercise therapy, locavore diet support, fundus, ABI, and carotid artery echocardiography.