📘 Onset and diagnosis of type 1 diabetes

The first signs, also called classic signs are "the 4 P's": polyuria (you urinate very much and often), polydipsia (extreme thirst you cannot quench), polyphagia (excessive hunger) and unexplained weight loss. You wake up multiple times at night to urinate and drink very much water per day. Paradoxically, although you eat more than usual, you lose several kilograms and cannot gain weight no matter what you do.

Other warning signs include extreme fatigue (as if you had run through the park), blurred vision (high blood sugar changes the lens refraction), recurrent infections (yeast, boil), fruity-smelling breath (ketones) and unexplained irritability. In children, bed-wetting returning after they have learned to control themselves is a warning signal that must be checked.

You lost weight because your cells cannot use the glucose from blood without sufficient insulin, although you have very high blood sugar. It's like dying of thirst in the middle of the ocean. There is water, but you cannot access it because it's too salty. Your body, desperate for energy, begins to dissolve and burn fat and muscle. Hence the rapid weight loss.

In addition, when blood sugar exceeds 180 mg/dl (10 mmol/L), kidneys eliminate glucose through urine, thus losing valuable calories. You also lose much water together with glucose (osmotic diuresis), which leads to dehydration and implicitly weight loss. Practically, although you eat much, your body remains in a state of continuous starvation.

Diabetic ketoacidosis at onset means that your body, lacking sufficient insulin, has started to massively burn fat for energy. At a certain point, when the insulin level in blood drops below an individual threshold hepatic production of ketone bodies is unlocked. Ketones are acids that lower blood pH, putting your life in danger. Up to half of newly diagnosed children present some degree of ketoacidosis.

Ketoacidosis symptoms include nausea, vomiting, diffuse abdominal pain, breathing deep and somewhat faster (Kussmaul breathing), confusion and in severe, rare cases, coma. Acetone smell in breathing is characteristic, but sometimes hard to notice. Ketoacidosis accompanied by vomiting requires immediate hospitalization for intravenous rehydration, insulin and correction of electrolyte imbalances. With prompt treatment, recovery is complete in 24-48 hours.

You must start insulin immediately after diagnosis, the same day or maximum the next day. Each day of delay means deterioration of remaining beta cells and risk of ketoacidosis. There is no "accommodation" period or temporary alternatives. Insulin is vital for survival, like oxygen for lungs.

In case of severe ketoacidosis you will start with intravenous insulin, in hospital. If onset is without ketoacidosis you can start with subcutaneous injections made at home, but with daily medical supervision or remotely. Initial doses are calculated prudently (e.g. 0.5 units/kg total) and adjusted quickly based on glycemic response.

Type 1 diabetes diagnosis is made on the association of a suggestive clinical picture with blood sugars in the diabetes range. Suggestive for type 1 diabetes are lower values for age, weight and time of symptom onset. Additionally there is an accelerated evolution of blood sugar increase, weight loss, increased water consumption and 24-hour urine volume.

To differentiate type 1 diabetes from other forms, autoantibodies can be tested (GAD, IA-2, IAA, ZnT8) and possibly C-peptide (decreased in type 1). In case of a clinical picture typical, especially in children, diagnosis is made without testing autoantibodies (if they are negative it doesn't change the diagnosis). Ketone bodies present in urine or blood support type 1 diabetes diagnosis. Genetic testing has no indication usually in stage 3 of the disease.

Yes, diagnostic errors are possible, especially in adults. Adolescents with significant overweight, with type 2 diabetes can be wrongly labeled as type 1. It can also happen inversely. Approximately 10% of young adults, initially diagnosed with type 2 actually have type 1 with slow evolution (LADA). Monogenic diabetes (MODY) is frequently confused with type 1 in young people (see large family burden with diabetes suggestive for MODY).

Clues for wrong diagnosis include: unexpectedly good treatment response, lack of ketoacidosis tendency in the absence of insulin, normal C-peptide after one year, family history strong of diabetes. If you have doubts, you can test autoantibodies and C-peptide. A second consultation at a specialized center (with these results) could help you.

Extreme thirst and frequent urination are caused by very high blood sugar that exceeds the kidneys' capacity to stop glucose from escaping into urine. Normally, kidneys retain all glucose in the body, but above 180 mg/dl (10 mmol/L) it starts to "leak" little by little into urine. Glucose in urine pulls water after it through osmosis, urinary bladder fills faster and you can reach even ten liters of urine per day.

This massive water loss leads to dehydration and increased blood concentration (osmolarity), which stimulates the thirst center in the brain. From thirst you drink very much water, but you cannot compensate losses. It's a vicious circle. The more you drink, the more you urinate. When you start insulin treatment the glucose loss stops and you no longer urinate much. Shortly afterwards thirst also passes.

Absolutely normal! Type 1 diabetes diagnosis is a major shock, that fundamentally changes your life. You go through the classic stages of trauma: denial ("it cannot be, it's a mistake"), anger ("why me?"), bargaining ("maybe it will disappear if..."), depression and finally acceptance. This process lasts weeks to months. It depends very much on you.

Feelings of being overwhelmed, fear, sadness and even panic are universal. Many people describe the sensation that "life is over". Important to know that these feelings are temporary. With time you will learn to manage diabetes and have a normal, fulfilled life. Consider specialized psychological counseling in the first months.

Diabetes diagnosis is made on the spot if you have a random blood sugar above 200 mg/dl (11.1 mmol/L) with classic symptoms. For fasting blood sugar above 126 mg/dl (7 mmol/L) OR blood sugar above 200 mg/dl (11.1 mmol/L) at 2 hours in tolerance test OR HbA1c above 6.5% (48 mmol/mol) reconfirmation is needed on another day or presence of two of them simultaneously. HbA1c can be below 6.5% (48 mmol/mol) in case of an abrupt and very recent onset.

Important is that in type 1 diabetes, unlike type 2, evolution from blood sugar normal to very high values is rapid (weeks). There is no "grey" zone (of prediabetes) prolonged. Once blood sugar starts to increase, deterioration is accelerated. Therefore, many are diagnosed in emergency with extreme blood sugar values and ketoacidosis.

Hospitalization depends on the severity of onset. If you have ketoacidosis with vomiting, hospitalization is mandatory. You need intravenous rehydration, insulin in infusion, intensive monitoring and correction of imbalances. Severe untreated ketoacidosis can be fatal in a very short time (hours-days).

Without ketoacidosis, you can be treated very well also in outpatient setting, if you have access to diabetes education, are clinically stable and can quickly learn the basics of insulin therapy. However, many doctors prefer short hospitalization (1-2 days) for stabilization, intensive education and observation of insulin response. For children, initial hospitalization is frequently recommended because access to outpatient education is limited.