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Diabetes in Humans
type 1, 2 and 3

Leo Rogier Verberne

2. Various types of diabetes

Diabetes mellitus is a group of metabolic diseases characterized by an increased blood glucose level (hyperglycemia). Which results from defects in insulin secretion, insulin action, or both (1). Insufficient insulin secretion is brought about when the β-cells in the pancreas function poorly or no longer function at all. If there is a shortage of insulin, then the organs absorb less or no glucose from the blood, which increases the blood glucose level. The World Health Organization (WHO) distinguishes between 60 different disorders that can cause hyperglycemia (4). Chronic hyperglycemia is associated with long-term damage to blood vessels and nerves, causing dysfunction of various organs like the eyes, kidneys and heart.

Juvenile diabetes (type 1 diabetes)
The number of juvenile diabetics in the Netherlands is estimated at 100,000 (6). So type 1 diabetes affects ± 0.55% of 18 million inhabitants. In the pancreas of juvenile diabetics, derailed T-lymphocytes attack the body’s own β-cells. Which is called an auto-immune reaction. When all β-cells have been shut down, the blood glucose level is no longer monitored and the production of insulin ceases. If left untreated, glucose can no longer be absorbed by the organs due to a lack of insulin and the blood glucose concentration increases tremendously as a consequence. The disorder is fatal within a few months unless external insulin is injected daily. Juvenile diabetes develops at an average age of 11 years (2-20) (9). Which explains the name. However, in some cases it does not manifest itself until middle age (>40). Therefore type 1 diabetes is a better name.

Adult-onset diabetes (type 2 diabetes)
The estimated number of humans in the Netherlands with manifest adult-onset diabetes is over 1 million. However, a similar number of people with prediabetes remains undiagnosed. Thus over 10% of all Dutch inhabitants are suffering (aware and unaware) from type 2 diabetes. In diabetes type 2, the functioning of the β-cells decreases slowly due to a degeneration process. Deposits of amyloid are formed in the islets of Langerhans (3). The degeneration process progresses insidiously and, as a result, the insulin level in the blood decreases very slowly, causing a dragging rise of the blood glucose level over years (9). It is not until the kidney threshold for glucose is exceeded that the classic symptoms of diabetes (excessive thirst and frequent urination of sugary urine) manifest themselves. And so it takes generally 6 years or more before prediabetes manifests itself as type 2 diabetes. But vascular damage like early arteriosclerosis, is already present in prediabetics (7). In adult-onset (pre)diabetics, insulin is present in the blood, but not enough to keep the glucose concentration at the normal level. Physical exercise can help to open up the glucose gates in the organ membranes, which reduces the blood glucose level in type 2 (pre)diabetics. Adult-onset diabetes usually does not become manifest until middle age (> 40 years). Which explains the name. But many years before it becomes actually manifest, it is ‘silently’ present. Sometimes it becomes already manifest in adolescents. That is why the disorder is preferably referred to as type 2 diabetes.

MODY (type 3 diabetes)
The number of people in the Netherlands suffering from MODY (Maturity-Onset Diabetes of the Young) is estimated at 20,000 (2). So about 0.1% of the Dutch people is affected by this third type of diabetes. It usually becomes manifest between the age of 10 and 25 (2), although it can be at a much younger age (5). That makes it look like type 1 diabetes. But the pancreas of type 3 diabetics still makes some insulin by itself. So the treatment of MODY differs from juvenile diabetes. It can be diagnosed by a DNA-test. But, in the present year 2017, that test is made in less than 5% of the people involved (2). Sometimes MODY is not discovered before the age of 40. Which makes it look like adult-onset diabetes. But its treatment is different, especially in terms of the dosage of medicines (if needed). Therefore it seems better to refer to MODY as type 3 diabetes.

Table 1. Age at which diabetes generally becomes manifest



Age (years)



2 - 20



> 40



10 - 25

Other types of diabetes
The 57 other types of diabetes (1) collectively make up a mere fraction of the Dutch diabetics. Gestational diabetes is the most frequently occurring in this group. Progesterone (pregnancy hormone) as well as large doses of corticosteroids (stress hormones) may cause diabetes, as these hormones increase the blood glucose concentration. In other cases, the increased blood sugar level is secondary to, for example, pancreatic cancer or an inflammation (pancreatitis); or it is the result of alcoholism. In these cases, the pancreas is damaged by the primary disease and β-cells subsequently shut down. Thus the ‘other forms of diabetes’ comprise a heterogeneous group of disorders that lead to an increased blood glucose concentration.

1. Juvenile diabetes (type 1 diabetes) affects about 100,000 humans in the Netherlands.
2. Adult-onset diabetes (type 2 diabetes) causes manifest diabetes in more than 1 million Dutch inhabitants; a similar number of prediabetics is undiagnosed.
3. MODY (type 3 diabetes) is estimated to affect about 20,000 of the Dutch people.
4. Juvenile diabetes develops as the result of an auto-immune reaction in the pancreas that shuts down the β-cells.
5. In adult-onset diabetes, the functioning of the β-cells decreases insidiously due to a degeneration process.

1. American Diabetes Association (2010). Diabetes Care Jan. 2010; vol. 33 supplement 1; S62-S69
Diagnosis and classification of diabetes mellitus
2. Erfocentrum (2017). MODY
3. Hayden MR and Tyagi SC (2001). "A" is for Amylin and Amyloid in type 2 diabetes mellitus.
4. International Expert Committee (2009). Diabetes Care July 2009; vol. 32 no. 7; p 1327-1334;
Report on the role of the A1C assay in the diagnosis of diabetes.
5. Koning E de (2011). MODY: veel diabetes binnen één familie
Bloedsuiker 26e jaargang nummer 2; p 10-11
6. Koning E de (2016). Hubrecht College. Amsterdam, 6th of April 2016
7. Kooy A. Diabetes, een mondiale pandemie: de progressieve ijsberg.
In: Diabetes Mellitus (2010); ISBN 978-90-313-7434-2; p 17
8. LUMC afdeling endocrinologie (2011). Diabetes mellitus type 2
9. Tack CJ en Stehouwer CDA. Diabetes mellitus. In: Interne geneeskunde; eds. Stehouwer, Koopmans en van der Meer. 14e druk (2010); ISBN 978-90-313-7360-4; p 835-865

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© Leo Rogier Verberne