TYPE 1 DIABETES – CAUSES, SYMPTOMS, AND POTENTIAL COMPLICATIONS
While Type 2 diabetes is often discussed in relation to lifestyle, Type 1 represents a different medical history: Here, the immune system determines who is affected—not diet or exercise. Currently, about 340,000 adults and over 37,000 children and adolescents in Germany live with Type 1 diabetes. Early signs can include unusually frequent urination or increased thirst. FITBOOK editor Michel Winges explains other symptoms, the causes of Type 1 diabetes mellitus, as well as possible consequences and treatment options.
Follow the FITBOOK channel on WhatsApp now!
Causes of Type 1 Diabetes Mellitus
The cause of Type 1 diabetes appears to be a combination of genetic predisposition and other external factors.1 Among other things, people with an acute enterovirus infection have a significantly higher risk of developing Type 1 diabetes.2 Another correlation is associated with a Coxsackievirus infection.3
In Type 1 diabetes, a specific process in the body is central: how sugar from food enters the cells. The answer leads directly to the hormone insulin. After eating, blood sugar levels rise because the food contains glucose. For this sugar to move from the blood into the body cells, the hormone insulin, produced in the pancreas—specifically in certain cells called beta cells—is needed.
Insulin acts like a key: It allows glucose to be absorbed from the blood into the cells, where it can be used as energy. Without insulin, the cell doors remain closed, and sugar accumulates in the blood.
In Type 1 diabetes, the problem arises because the immune system—our defense against diseases—makes a mistake: It mistakenly considers its own beta cells dangerous and destroys them. As a result, little or no insulin is produced. Why the immune system reacts this way is still not fully understood; experts refer to it as an autoimmune reaction.
Therefore, people with Type 1 diabetes must supply the missing insulin externally for life, usually through injections or an insulin pump.4 Only then can sugar enter the cells again, and the body be adequately supplied with energy.
Also interesting: Popular spice can lower blood sugar and help with weight loss
Symptoms
The symptoms can appear very suddenly and worsen quickly.
- Polyuria: needing to urinate more frequently than the average for one’s age
- Polydipsia: increased thirst accompanied by excessive drinking
- Polyphagia: abnormally increased food intake
- Fatigue, weakness, and lack of drive
- Headaches
- Abdominal pain, with possible nausea
- Weight loss
- Fungal skin infection
- Visual disturbances
Diagnosis
The doctor first conducts a systematic interview to assess the patient’s health status. Complaints, medical history, allergies, living conditions, and genetic risk are recorded. This is followed by a physical examination: seeing, hearing, touching, and smelling.
To clarify a possible diabetes mellitus, the blood sugar level is checked. An initial orienting measurement can be done with a small prick on the fingertip. This provides an indication of the current blood sugar level. However, for an accurate diagnosis, a blood sample is required in a fasting state, after at least eight hours without food.
If an elevated fasting blood sugar level is detected, it indicates diabetes. Additionally, the so-called HbA1c value is often determined. It provides information about the average blood sugar concentration over the past two to three months.
Type 1 diabetes often begins years before the actual diagnosis, without any noticeable symptoms. A large long-term study with thousands of children from Germany, Finland, and the U.S. shows: In children with an increased genetic risk, so-called islet autoantibodies can be detected in the blood as early as infancy.5 The islet autoantibodies act as a marker, but they do not actively destroy the beta cells; this occurs years, sometimes decades later, when T-cells mistakenly see the beta cells as enemies. The islet autoantibodies are thus considered early signs of the development of Type 1 diabetes mellitus. The risk is particularly evident when several of these autoantibodies are present simultaneously. About 70 percent of affected children developed the disease within ten years. After 15 years, the rate was already over 84 percent, and by the end of the observation period, nearly 20 years later, almost all children had developed diabetes.
What can be concluded from the study is that there is a long time window in which targeted preventive measures can be taken. However, the outbreak cannot be prevented.
Therapy
Unfortunately, Type 1 diabetes cannot be cured, but there are now various ways to manage it. Not only are there several types of insulin available, but also different application techniques. The foundation remains the same: Patients must regularly measure their blood sugar and inject insulin accordingly. Only in this way can the blood sugar level be kept within the target range over the long term.
Forms of Insulin Treatment
Diabetics generally have a choice between two treatment forms. Today, the majority of those affected opt for intensive therapy. However, which method is better cannot be said across the board—it depends heavily on individual circumstances and personal needs.
Conventional Treatment
The conventional therapy relies on a rather rigid routine. It only works if daily life is very consistent—fixed meals, fixed injection times, fixed activities.
Here, insulin is usually injected twice a day—often a mixed insulin that works over hours. For the effect to be optimal and to avoid hypoglycemia, patients must eat precisely defined amounts of carbohydrates at specific times. Spontaneous physical activity is also not allowed—it must be planned in advance to avoid problems.
In short: This therapy requires discipline and a fairly structured daily routine. Spontaneity is hardly possible, but handling is relatively simple.
Intensive Insulin Therapy
The intensive therapy is more flexible—it adapts to life, not the other way around. Here, a long-acting insulin for the basic need (basal insulin) is used, and additionally, fast-acting insulin is injected before meals—depending on what and how much is eaten, and what the current blood sugar level is.
The advantages: Eating, exercise, and daily planning are much freer. However, it requires more thought, calculation, and attention. Once familiar with this method, it is manageable in everyday life—whether at school, work, or leisure.
Also interesting: Alexander Zverev after Wimbledon exit: “I feel quite alone in life”
What Aids Are Available?
Insulin Pens
Insulin pens are easy-to-use injection aids, about the size of a ballpoint pen. They allow insulin to be administered quickly, precisely, and almost painlessly. There are semi-automatic and fully automatic models, as well as pens with digital functions like dose storage or smartphone connectivity.
Insulin Pump
Insulin pumps deliver small amounts of insulin around the clock through a catheter under the skin. Additionally, meal boluses can be administered at the push of a button. They offer more flexibility than pens and are recommended for frequent hypoglycemia, irregular daily routines, and children.
Hybrid Closed-Loop System
These systems combine an insulin pump with continuous glucose monitoring (CGM). They automatically adjust insulin delivery based on glucose levels. However, meals must still be entered manually. According to study findings, a closed-loop system improves blood sugar management and reduces the risk of hypoglycemia.6
Patch Pumps
Patch pumps are small devices that do not require a tube and are directly adhered to the skin. They can be controlled via remote control and are less noticeable in everyday life. The entire device is replaced every three days.
Secondary Diseases
There are a number of secondary diseases that can occur due to Type 1 diabetes mellitus. In untreated diabetes mellitus, ketoacidosis can develop, especially when there is an absolute insulin deficiency.7 This results in symptoms such as confusion, deep and labored breathing, and a so-called acetone smell, reminiscent of nail polish remover or overripe fruit.
Sexual Limitations
In Men
That Type 1 diabetes affects sexuality is not an isolated case—but rather widespread. An Italian study from 2025 shows: Almost every second man with Type 1 diabetes is affected by erectile dysfunction. Over a quarter of the participants also suffered from a severe form of erectile dysfunction, meaning a pronounced and persistent impairment.
A total of 68 men aged 18 and older with different diabetes therapies were examined. All participants completed the internationally standardized questionnaire for assessing sexual function. The analysis shows: The likelihood of sexual dysfunction increases significantly with age. Men between 41 and 60 years scored significantly lower in almost all areas of sexual function (e.g., erectile ability, desire, satisfaction) than younger participants.
Neither blood sugar control nor the type of insulin therapy (pen or pump) had a measurable impact on the frequency of erectile dysfunction. Instead, it was shown: Relationship status played a major role. Men living in a committed partnership, especially in a new relationship, had significantly better scores in desire, satisfaction, and erectile ability than single men.
Unfortunately, the study also shows that this is still a major taboo topic: More than three-quarters of the men had never discussed their sexual problems with medical professionals before the study.8
In Women
This is also a major taboo topic for women—and research here is significantly less developed than for the male counterpart. However, a study showed that more than one in three women with Type 1 diabetes suffers from sexual dysfunction. This is a significantly higher rate than among healthy peers: just over 36 percent compared to just over five percent.
The same questionnaire was used in the study as in the study on male limitations. The women consistently scored lower in desire, arousal, lubrication (moisture), and orgasm than the healthy control group. Desire and physical arousal, in particular, differed greatly.
As with the men, neither blood sugar control nor the type of insulin therapy (pen or pump) made a significant difference for the women. Also notable was a connection with diabetic late effects such as neuropathies: Women with secondary damage reported more frequent problems during intercourse, such as reduced sensitivity or vaginal dryness.9
Diabetic Retinopathy
The likelihood of a Type 1 diabetic developing diabetic retinopathy over their lifetime is about 25 percent. It occurs because diabetes can damage the smallest blood vessels in the eyes. Initially, those affected often do not notice this, but over time it can lead to mild vision problems up to blindness.
Diabetic retinopathy can manifest in various ways: In addition to the typical vascular changes, the macula (maculopathy) can also be affected. Additionally, people with diabetes are more likely to develop cataracts and glaucoma. Inflammations of the upper and lower eyelids can also occur.
Because of all these possible consequences, the German Diabetes Society recommends that people with Type 1 diabetes have regular eye check-ups starting at age 11 or at the latest five years after diagnosis.10
Diabetic Foot
The so-called diabetic foot syndrome occurs when persistently high blood sugar levels damage the nerves and blood vessels in the legs. As a result, diabetics do not properly feel pressure points, small injuries, or ingrown nails. The wounds can thus spread unnoticed. Additionally, the tissue is poorly supplied with blood, which further complicates healing. In the worst case, tissue can die, and amputation may be necessary. To prevent this, feet should be checked regularly. Early signs of diabetic feet include dry and/or cracked skin, calluses, or poorly healing wounds on toes, heels, or balls of the feet.
Brain and Psyche
A diabetes diagnosis can cause significant stress for those affected. Many are overwhelmed by the daily demands and adjustments that a diagnosis means for the rest of their lives. This constant emotional burden and stress are referred to in the professional world as diabetes distress.
In addition, other secondary diseases can occur, including depression. People with diabetes have a significantly increased risk of developing depression. The risk for diabetics is on average 33 percent higher than for people without diabetes.11
Besides the psyche, the brain is also structurally and functionally affected. Studies indicate that diabetes increases the risk of mild cognitive impairments. With a long course of the disease and in later age, it is particularly concerning that diabetics are significantly more likely to develop dementia—up to 1.7 times more likely to develop forms of dementia. The risk of vascular dementia is more than doubled.12,13
Skin Diseases
Up to 80 percent of all people with diabetes experience pathological changes in the skin over their lifetime. The cause is, on the one hand, the persistent high sugar levels in the body, but certain insulins or other accompanying medications can also trigger it. In Type 1 diabetes, autoimmune-related changes occur more frequently. These include vitiligo, necrobiosis lipoidica, and also—not primarily autoimmune—scleroderma.
Other skin diseases that can occur include:
Fungal infections: Candida infections (often in the mouth, skin folds, hair roots, or genital area in men and women); tinea/dermatophytosis (nail fungus or athlete’s foot)
Bacterial infections: Erysipelas (bright red, warmer than the surrounding area, and rapidly spreading); erythrasma (mainly in skin folds or areas with heavy sweating)
Pseudacanthosis nigricans: usually a result of insulin resistance and initially affects the neck region, later also armpits, joint bends, or groin area. Gray-brown and velvety patches on the skin.
Xanthomas: Result of a lipid metabolism disorder, causing nodular fat deposits in the skin, these are orange-yellowish shimmering but harmless.
Itching: About one-third of all diabetics suffer from dry and itchy skin. Scratching only worsens the itching.
Pigment disorders: Reddish to brown spots on the lower legs, but they are painless.
Dental Health
Diabetes can also affect dental health and cause so-called periodontitis and gum inflammation. Periodontitis progresses slowly, leads to bone loss, and is often only noticed when the first teeth become loose. Therefore, regular brushing is essential, and an annual check-up is recommended. People with diabetes have a significantly increased risk of developing periodontitis—three times more often than non-diabetics. About 75 percent of all diabetics develop inflammation of the oral mucosa over their lifetime.
Cardiovascular Diseases
Cardiovascular diseases are among the most common secondary problems in diabetes mellitus—even in Type 1. High blood sugar levels damage the inner walls of the arteries in the long term. Due to vascular narrowing, also called arteriosclerosis, blood flow is hindered. The result is an increase in heart attacks, strokes, or peripheral circulatory disorders.
The vascular damage usually develops slowly and remains unnoticed for a long time. Only when they are advanced do symptoms appear, and they vary depending on the affected organ. Chest pain on exertion, dizziness, or muscle pain in the legs can be warning signs. The latter are typical for the so-called “window shopping disease”—a common term for circulatory disorders in the leg arteries. Regular monitoring of vascular health is particularly important for prevention.
In addition to good blood sugar control, a healthy lifestyle plays a crucial role: balanced diet, exercise, smoking cessation—and, if necessary, targeted medication therapy. According to the ESC/ESH guidelines 2018, people with diabetes should aim for a blood pressure target of below 140/80 mmHg—ideally 130/80 mmHg, if well tolerated.14
Liver
In Type 1 diabetics, the occurrence of fatty liver is less common than in Type 2 diabetics, but still a dangerous secondary disease. The main cause is often insulin resistance, which disrupts fat metabolism. The risk is increased by overweight, lack of exercise, unhealthy diet, or persistently high blood sugar levels.
There are hardly any typical warning signs. Indications can be fatigue, a feeling of fullness, or pressure in the upper abdomen. An ultrasound usually provides clarity in case of uncertainty. The good news is that a consistent lifestyle change can achieve a lot. A weight loss of five to ten percent can relieve the liver. A weight loss of ten percent can even reverse non-alcoholic fatty liver inflammation.15
Lungs
Studies show that Type 1 diabetes measurably worsens lung function, even in children. The results of a meta-analysis with over 2,500 participants speak clearly: People with Type 1 diabetes have, on average, lower values in several lung function tests—including lung volume, airflow, and oxygen exchange.16 Small airways and the lung’s ability to absorb oxygen into the blood are particularly affected. This is likely due to persistent inflammatory processes and changes in the fine blood vessels of the lung. The lung thus shows similar damage to other known target organs in diabetes—such as eyes or kidneys.17 Even in children with Type 1 diabetes, limited oxygen uptake, poorer endurance, and increased inflammatory markers in the lung have been observed.18
Also interesting: New form of diabetes found—many patients previously misdiagnosed
Cancer
While the connection is better documented in Type 2 diabetes, studies increasingly show a slightly increased cancer incidence in people with Type 1 diabetes. In particular, the following cancers occur more frequently in Type 1 diabetics than in non-diabetics: liver, pancreas, kidney, stomach, as well as leukemia and thyroid cancer.
The causes are not clearly understood. High blood sugar levels and insulin levels are primarily discussed as possible influencing factors. Insulin acts not only as a blood sugar regulator but also as a growth factor, suggesting that a persistently elevated insulin level (such as with a high daily insulin dose) could influence cell growth.19 Moreover, hyperglycemia promotes inflammatory processes in the body, which can also increase cancer risk.20
A large-scale study from five countries confirms: Women with Type 1 diabetes have an approximately seven percent increased overall risk for cancer, while men are about on par with the general population. The greatest differences are seen in liver, pancreatic, and stomach cancer—here, the risk was sometimes twice as high. At the same time, men with Type 1 diabetes had a significantly lower risk for prostate cancer, and women for breast cancer.21
Kidneys
The kidneys are particularly sensitive. About 20 to 40 percent of those affected develop so-called diabetic nephropathy over time, a chronic and insidiously beginning kidney damage. The persistently elevated blood sugar levels damage the fine blood vessels in the kidney glomeruli. As a result, proteins enter the urine because the kidney’s filtering function diminishes. After five years of diabetes, an annual check-up should be conducted to detect early signs as quickly as possible.
Nerve Damage
Nerve damage is among the most common secondary diseases in Type 1 diabetes, alongside cardiovascular diseases. Depending on which areas are affected, two forms are distinguished: peripheral and autonomic neuropathy. Neuropathies often develop insidiously. Experts therefore recommend regular check-ups starting five years after diagnosis. Stable blood sugar, exercise, and smoking cessation can help prevent them.22
Peripheral Form
The peripheral form usually affects the feet and legs and manifests as tingling, burning, numbness, or pain. The symptoms occur mainly at night. As a result, small injuries are easily overlooked, increasing the risk of diabetic foot syndrome.
Autonomic Form
Autonomic neuropathy affects internal organs: heart, stomach, bladder, or sexual organs. Possible consequences include digestive problems, circulatory disorders, or sexual limitations.
The post Type 1 Diabetes – Causes, Symptoms, and Potential Complications appeared first on FITBOOK.
2025-08-05T12:05:12Z