Type 1 diabetes is a chronic autoimmune disease in which the body's own immune system destroys the insulin-producing beta cells in the pancreas. Without beta cells, the body generally can no longer make its own insulin — and without insulin, glucose (sugar) cannot move from the blood into the cells, where it's needed as energy.
Insulin must never be stopped on your own
Without insulin from outside, Type 1 diabetes is generally life-threatening. Those affected usually need to take insulin for life — by insulin pen or insulin pump. Always discuss changes to the treatment plan with your diabetes team.
No fault — it's an autoimmune disease
Type 1 diabetes is NOT caused by lifestyle, diet or "too much sugar." It is an autoimmune disease that can in principle affect anyone.
In Germany, around 341,000 adults and approximately 37,000 children and adolescents live with Type 1 diabetes. Each year, around 4,000 children and adolescents are newly diagnosed; numbers have been rising slightly for years.¹˒⁵
2. Difference from Type 2
Feature
Type 1 diabetes
Type 2 diabetes
Cause
Autoimmune disease — absolute insulin deficiency
Insulin resistance + relative insulin deficiency
Age
Usually childhood/adolescence; can occur at any age (including LADA)
Often middle or older age
Lifestyle
Not caused by lifestyle
Often combined with overweight
Insulin
Generally required for life
Initially lifestyle/tablets; insulin usually only in later stages
Type 1 diabetes generally doesn't develop overnight. The autoimmune process often begins years before the first symptoms. Since the approval of teplizumab, this knowledge is for the first time also therapeutically relevant.⁶
Stage 1Autoimmunity — blood glucose still normal
At least two typical autoantibodies against beta cells are detectable in the blood (e.g. GAD antibodies, IA-2 antibodies, ZnT8 antibodies, IAA). Blood glucose is still normal, and there are generally no symptoms. The lifetime risk of progressing to Stage 3 is significantly elevated in this group.
Stage 2Dysglycemia — blood glucose abnormal, but not yet diabetes
Autoantibodies are positive AND blood glucose is already abnormal (e.g. impaired glucose tolerance) — but there is no manifest diabetes yet. Generally still no symptoms.
Teplizumab can intervene here
At this stage, according to the prescribing information, teplizumab can delay progression to Stage 3 by an average of about two years.⁶
The classic symptoms appear — excessive thirst, frequent urination, weight loss. From this point onwards, lifelong insulin therapy is generally required. In a relevant proportion of children, the first manifestation presents as ketoacidosis (an emergency — see section 5).
Early-detection programs
Programs like the Fr1da study in Germany or the European EDENT1FI project test children for autoantibodies to identify Stages 1 and 2 — and to enable early intervention in the future.
4. Causes and risk factors
Genetic predisposition
Certain HLA genes (including HLA-DR3 and DR4) increase the risk of Type 1 diabetes. If one parent is affected, there is a moderately increased risk for the children. In identical twins, the concordance is significantly higher. Nevertheless, the great majority of new cases occur in families without known Type 1 diabetes.¹
Autoimmune process
The immune system forms autoantibodies against the beta cells — this process often begins in early childhood and can be detectable years before the first symptoms. Typical autoantibodies: GAD antibodies, IA-2 antibodies, ZnT8 antibodies and IAA. They serve as early markers and are a prerequisite for possible teplizumab therapy.⁶
Possible triggers
Viral infections (among others, enteroviruses) are discussed as possible triggers of the autoimmune process
Other environmental factors (e.g. vitamin D status, dietary proteins in infancy) are being researched — the evidence is so far inconsistent
Not modifiable: Type 1 diabetes can neither be prevented nor caused by diet or exercise
5. Symptoms and ketoacidosis warning
Symptoms in Type 1 generally develop significantly faster than in Type 2 — often within days to weeks:
Vision problems due to temporary changes in the lens of the eye
Ketoacidosis (DKA) — a life-threatening emergency
When insulin is missing, the body falls back on fat as an energy source. This produces ketones that make the blood acidic (acidosis). In a relevant proportion of children, Type 1 diabetes is first diagnosed in the setting of ketoacidosis.¹
Nausea, vomiting, abdominal pain
Fruity-sweet breath odor (acetone)
Deep, rapid breathing (Kussmaul breathing)
Impaired consciousness up to coma
Ketoacidosis — call 112 immediately!
Ketoacidosis is a medical emergency. In children with thirst, frequent urination and weight loss, blood glucose should generally be measured immediately.
6. Diagnosis
The diagnosis is generally made using a combination of clinical picture and lab values:
Fasting blood glucose ≥ 126 mg/dL (7.0 mmol/L) or random blood glucose ≥ 200 mg/dL with typical symptoms¹˒⁷
HbA1c ≥ 6.5% as a "long-term blood glucose." Caution: with very rapid onset, HbA1c may still be normal
Autoantibodies (e.g. GAD antibodies, IA-2 antibodies, ZnT8 antibodies) — usually positive in Type 1, generally negative in Type 2
C-peptide — low or barely measurable in Type 1 (no endogenous insulin); usually normal or elevated in Type 2
Don't miss LADA
In adults with a first manifestation, autoantibody testing is generally important — otherwise LADA (Latent Autoimmune Diabetes in Adults) can be incorrectly classified as Type 2.
Without insulin, Type 1 diabetes cannot be treated. Which insulin regimen, dose and insulin type are used in each case is always decided by your treating diabetes team.¹
Basal insulin (long-acting insulin)
Covers basic insulin needs throughout the day and night. Examples: insulin glargine, insulin degludec, insulin detemir. NEW: Insulin icodec has been available in the EU since 2025 as the first basal insulin given only once per week — its place in therapy is currently being discussed in the guidelines.
Bolus insulin (mealtime insulin)
Generally used with meals. The exact dose depends on the carbohydrate amount and the current blood glucose value (individual training required). Examples: insulin lispro, insulin aspart, insulin glulisine.
MDI (multiple daily injections, also called "ICT" in German practice) — basal–bolus principle
Combination of basal and bolus insulin. Considered the standard of modern Type 1 therapy and requires structured training: measuring blood glucose, estimating carbohydrates (in Germany counted in KE/BE units) and calculating corrections.¹
Insulin pump therapy (CSII)
A small pump continuously delivers insulin through a catheter. The basal rate runs in the background; the mealtime bolus is delivered at the touch of a button. Pumps are widely used in Germany, particularly in children and adolescents. Tubeless patch-pump systems (e.g. Omnipod 5) stick directly onto the skin.
Never stop insulin on your own
Not even during illness, low appetite or "good" values. Without insulin, a life-threatening ketoacidosis can develop within a few hours. Always discuss changes to the treatment plan with your diabetes team. Learn more: Stopping medication.
8. Modern technology: CGM and AID systems
Continuous Glucose Monitoring (CGM)
A CGM sensor is placed under the skin and measures tissue glucose every 1–5 minutes. The values are sent wirelessly to a smartphone. CGM has significantly changed Type 1 therapy in recent years.¹
Routine fingerstick testing is often no longer needed
Trend arrows show whether glucose is rising, falling or stable
Alarms can warn of hypo- or hyperglycemia — including at night
Follow function: family members can monitor values remotely (e.g. parents of children with Type 1)
AID systems combine a CGM sensor, an algorithm and an insulin pump: the sensor measures, the algorithm calculates, the pump delivers the adjusted dose. Mealtime insulin is generally still entered manually — hence "hybrid."
2025 study data: AID improves outcomes
Study data (including Karges et al., Lancet Diabetes & Endocrinology, 2025) show that under AID therapy, time in range is greater, severe hypoglycemic episodes are rarer and HbA1c is often lower than under purely manual therapy.³ The German guideline says an AID system should be offered when MDI with CGM does not reach the treatment targets.
System
Manufacturer
CGM compatibility
Notable features
MiniMed 780G
Medtronic
Guardian 4 / Simplera Sync
Fully automatic correction bolus
t:slim X2 + Control-IQ
Tandem
Dexcom G6/G7
Sleep and activity modes
Omnipod 5
Insulet
Dexcom G6/G7
Tubeless patch-pump system; from age 2
mylife Loop + CamAPS FX
Ypsomed
Dexcom G6/G7
CamAPS FX also on iPhone; from age 1
Table scrolls to the right
9. NEW: teplizumab (Teizeild) — delaying Type 1 diabetes
EU approval January 8, 2026 — available in Germany since February 16, 2026
With teplizumab, for the first time a medication is available that, according to current evidence, can delay the onset of Type 1 diabetes in a narrowly defined patient group at Stage 2.
Teplizumab (Teizeild in EU / Tzield in US) — anti-CD3 antibody
What it is: A monoclonal antibody that binds to the CD3 receptor on T lymphocytes and can intervene in the autoimmune process For whom: Per EU approval, for adults and children from age 8 with Type 1 diabetes at Stage 2 — i.e. at least two autoantibodies positive AND abnormal blood glucose (dysglycemia), but not yet manifest diabetes⁶ Efficacy (TN-10 study, n=76): Delay in progression to Stage 3 by a median of around 2 years. At the end of the study: ~57% of the teplizumab group were still at Stage 2 vs. ~28% under placebo⁶ Use: A single treatment cycle with daily intravenous infusions over 14 days. After that, generally no further dosing. Administered exclusively in specialized centers. Side effects: Commonly transient lymphopenia, leukopenia and skin rash. Rarely: cytokine release syndrome. Regular lab monitoring required. Manufacturer: Sanofi. Approved in the US since 2022 as Tzield.
Important: not a cure — only for Stage 2
Teplizumab does NOT cure Type 1 diabetes and generally does not prevent onset permanently — it can delay progression to Stage 3 by an average of around two years. The medication is approved exclusively for Stage 2, not for manifest Type 1 diabetes. A prerequisite is early detection through autoantibody screening.
10. Living with Type 1 diabetes
Nutrition: A special "diabetic diet" is generally not necessary — what matters is estimating the carbohydrates in a meal and adjusting insulin accordingly (after medical training). High-fiber foods often raise blood glucose more slowly.
Sport: Physical activity is generally possible with Type 1 and is often recommended. Important: good planning, measure blood glucose before exercise, take carbohydrates if needed, adjust insulin dose, keep fast-acting carbohydrates on hand for emergencies.
Alcohol: Alcohol can lower blood glucose — the risk of nocturnal hypoglycemia may be elevated. Learn more: Medication and alcohol.
Travel: Transport insulin cool (do not freeze!); take an adequate reserve and a multilingual doctor's certificate for insulin, syringes, pump and CGM. Learn more: Medication when traveling.
Driver's license and work: Type 1 diabetes is generally not a fundamental obstacle. A blood glucose check before driving and easily accessible fast-acting carbohydrates are standard. Special rules apply to certain occupations.
Emergency management
With warning signs of hypoglycemia (trembling, sweating, palpitations, ravenous hunger): take fast-acting carbohydrates immediately and re-measure after a few minutes. In severe hypoglycemia with loss of consciousness: call 112 and — if a trained person is nearby — administer a glucagon rescue medication (e.g. as a nasal spray). Never put anything in the mouth of an unconscious person. If ketoacidosis is suspected, also call 112 immediately.
11. Type 1 diabetes in children
Type 1 diabetes is one of the most common metabolic conditions in childhood and adolescence.⁵
Onset is often sudden; in a relevant proportion of cases, the condition is first diagnosed in the setting of ketoacidosis
Insulin pumps and AID systems are widely used in childhood in Germany; Omnipod 5 is approved from age 2, CamAPS FX from age 1
CGM is generally considered standard in this age group; the follow function allows parents to monitor values
Structured education for children AND parents is important — estimating carbohydrates, dosing insulin, recognizing hypoglycemic episodes
At daycare or school, rescue medications (e.g. glucagon) and fast-acting carbohydrates should be readily available; teaching staff should be informed
During puberty, metabolic control can usually become more difficult — hormonal fluctuations and emotional strain both play a role
Mental health issues and eating disorders (e.g. "diabulimia") should be discussed early with the diabetes team
NEW: With a family history, autoantibody screening can be sensible — in rare cases, treatment with teplizumab may be an option at Stage 2⁶
How brite helps you with Type 1 diabetes
brite brings structure to your diabetes therapy — from basal insulin to your diabetes specialist appointment.
Medication reminders — basal insulin, bolus insulin, CGM sensor change, pump set change: brite reliably reminds you. Set up a reminder
Interaction check — check insulin in combination with other medications (e.g. cortisone can raise blood glucose) for free. Check now
Health tracking — document blood glucose, HbA1c, hypoglycemic episodes, sensor days and symptoms in a structured way. Track your history
Digital medication plan — insulin regimen, CGM, pump and other medications clearly laid out for diabetes specialist, GP and emergency department. Go to medication plan
According to current knowledge, Type 1 diabetes is generally not curable — those affected usually need insulin for life. Teplizumab (Teizeild) can delay onset by an average of about two years in a narrowly defined group at Stage 2, but does not cure. Research into other approaches (e.g. beta cell regeneration) is ongoing.⁶
Teplizumab is the first antibody approved in the EU (approval January 8, 2026, available in Germany since February 16, 2026) that can delay the onset of Type 1 diabetes at Stage 2. Approved for children from age 8 and adults with confirmed autoantibodies AND abnormal blood glucose values, but not yet with manifest diabetes. Treatment consists of a single 14-day cycle with daily infusions in a specialized center.⁶
In most cases yes. With modern therapy (insulin, CGM, AID systems), a largely normal life is usually possible — including sport, travel and many occupations. The technical options have advanced significantly in recent years.¹
The combination of a CGM sensor, an algorithm and an insulin pump. The algorithm adjusts the insulin dose automatically at short intervals based on the current glucose value. Mealtime insulin is generally still entered manually — hence "hybrid." Current systems available in Germany: MiniMed 780G, Omnipod 5, t:slim X2 with Control-IQ and mylife Loop with CamAPS FX.¹
With warning signs, take fast-acting carbohydrates immediately (e.g. glucose tablets, a sugary drink), wait a few minutes and re-measure. In severe hypoglycemia with loss of consciousness: call 112 and — if someone nearby is trained — administer a glucagon rescue medication. Never put anything in the mouth of an unconscious person.
Yes — sport is generally possible with Type 1 and is often recommended. Important: planning, an adjusted insulin dose and fast-acting carbohydrates on hand. AID systems often offer special activity modes. Fine-tuning should always be done together with your diabetes team.
LADA (Latent Autoimmune Diabetes in Adults) is a form of autoimmune diabetes that begins in adulthood and often initially looks like Type 2 diabetes. Typical: detectable autoantibodies in usually lean patients without marked insulin resistance. Distinction is made through autoantibody testing and C-peptide.
This should be discussed individually with your pediatrician or a diabetes clinic — particularly with first-degree relatives with Type 1 diabetes. Programs like the Fr1da study offer partly free testing. Since the approval of teplizumab, early detection has for the first time a potential therapeutic consequence.⁶
S3 Guideline on Therapy of Type 1 Diabetes (DDG, AWMF reg. no. 057-013, 2023). awmf.org
German Diabetes Association (DDG): Diabetes Health Report and Factsheet. ddg.info
Karges B. et al.: Hybrid closed-loop systems and hypoglycaemia risk in young people with type 1 diabetes — Lancet Diabetes & Endocrinology (2025). dzd-ev.de
diabinfo.de — Information on Type 1 Diabetes (DZD/HMGU/DDZ). diabinfo.de
Robert Koch Institute: National Diabetes Surveillance — Data on Children and Adolescents. diabsurv.rki.de
Sanofi / European Commission: EU approval of Teizeild (teplizumab) — January 2026. pharmazeutische-zeitung.de
National Disease Management Guideline on Type 2 Diabetes (ÄZQ/AWMF, December 2024) — supplementary for diagnostic criteria. awmf.org
Medical disclaimer: This article is for general information only and is not a substitute for medical advice, diagnosis or treatment. Insulin doses, the choice of insulin regimen, the indication for pump or AID therapy and the decision about teplizumab are always determined individually by your treating diabetes team. If diabetic ketoacidosis is suspected (fruity-sweet breath odor, vomiting, deep rapid breathing, impaired consciousness) or in severe hypoglycemia, call emergency services (112 in the EU/UK) immediately. Insulin generally must never be stopped on your own. Last updated: April 2026.
