Understanding type 1 and type 2 diabetes
Diabetes mellitus is a condition that causes chronically raised levels of glucose in the body due to either a lack of insulin in the body or either to a fault in the mechanism of insulin action. This decreases the overall life expectancy by 25%, it affects roughly 2% of the population and this figure is set to double over the next 10 years. There are various effects diabetes can have on an individual.
There are two main types of diabetics
The first is known as type 1 insulin dependant diabetics, this affects 20% of all diabetics and is usually present in childhood, this tends to be characterised by destruction of insulin cells via the immune system.
There are also type 2 diabetes which is known as non insulin dependant diabetes mellitus (NIDDM), this affects 80% of all diabetics and 85% tend to be obese. This is usually characterised by insulin resistance in cells, this usually occurs in adults during middle age.
Causes of type 1 diabetes
90% of the time type 1 diabetes is caused by the autoimmune destruction of the beta cells and thus these cells cannot secrete insulin. There tends to be links between different population groups. For example oriental people tend to get diabetes a lot less than Scandinavian. There is also a strong link in families with mother fathers, siblings, fraternal twins, and the highest link is with identical twins who 50% of the time will contract type 1 diabetes, if one twin contracts diabetes. There is also environmental issues such as toxins, viruses and food such as cows milk and nitrosamines which can help contribute to the causes.
Progression of type 1 diabetes
Initially there is the genetic predisposition and over time the mass of beta cells decrease. Initially there is Insulitis and cell injury then prediabetes and finally diabetes. This is diagnosed through a glucose intolerance test.
Progression of type 2 diabetes
This is usually caused by the cells reduced response to insulin as it becomes more and more insulin resistance. This is a gradual process. This occurs to target tissues. There is also known evidence that in the beta cells there is reduced first phase and impaired second phase which causes problem in the production of insulin from proinsulin.
There is a strong link with obesity and it is seen that as obesity occurs gradually, insulin resistance increase’s and insulin production reduces.
Insulin resistance leads to the defects in the cell. As insulin resistance occurs this leads to hyperinsulemia which causes beta cell exhaustion and thus a reduction in insulin production. This is typical of obese people.
Causes for type 2 diabetes
- Genetic
You can analyse genetic causes by looking at identical twins. In monozygotic twins there is an 80% concordance rate with IGT (A gene) and for dizygotic twins there is a 20% concordance rate. This shows that there is no one gene responsible for causing diabetes.
- Environmental
There tends to be a link with economic prosperity and obesity in the incidence of type 2 diabetes in patients. There is 50% concordance rate in pima Indians
Also the thrifty hypothesis was developed which states low calorific intake relates to diabetes because it results in increased fats being deposited in higher amounts as a survival mechanism for food shortages.
Clinical and biochemical features of type 1 and type 2 diabetes.
- Type 1 diabetes
There tends to be a sudden onset which has strong symptoms such as weight loss, the patient tends to be lean, and autoimmunity can be detected.
- Type 2 diabetes
There tends to be a gradual onset, the symptoms may not be present, the patient is usually overweight and they have no recent weight loss. There are no markers for autoimmunity.
Diagnosis
You start by initially testing random blood glucose levels. And if it Is 15mmol then the patient is diabetic, if it is between 8-12mmol you take and (OGTT) oral glucose tolerance test (75g) and if the patient is intolerant you retest if not the patient is non diabetic.
- The oral glucose tolerance test
This test involves the patient fasting overnight. The following morning a blood glucose test is taken and then glucose levels are measured. The patient is diabetic if it is above 7mmol, you can also consume 75g of protein and measure glucose levels 2 hours later. If the reading is over 11.1 mmol then patient is diabetic, if the reading is in between 7.6mmol and 11.1 the patient has impaired glucose tolerance.
Management of diabetes
For type 1 diabetes the patient can take insulin in the form of injection and also there is the possibility of a islet transplantation.
For type 2 diabetes exercise and diet is the key and also insulin injections can be taken, in addition to this the patient can take 5 types of hypoglycaemic drugs, to help deal with the symptoms.
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