What is type 2* Diabetes?
Type 2 diabetes is a chronic metabolic disorder which is characterized by insulin insensitivity (a condition in which cells fail to respond to insulin), declining insulin production and eventual pancreatic β-cell failure. Normally the β-cells sense glucose levels and release insulin, which promotes the uptake of glucose from the blood. This helps to maintain normal levels of blood sugar. In case of insulin insensitivity and declining production, the level of blood glucose will be abnormally high. This can result in long term complications such as cardiovascular disease, kidney failure, blindness and poor blood flow to limbs.
Type 2 diabetes is a progressive disease, the major cause being decline in β-cell function. Treatment includes lifestyle modifications, medication that lowers blood glucose, insulin sensitizers and insulin. Type 2 diabetes cases account for 90% of all diabetes cases.
* Type 2 diabetes usually develops later in life and is a metabolic disorder often caused by lifestyle. Type 1 diabetes usually develops in early childhood and adolescence and is an autoimmune disorder.
Genotype and type 2 diabetes risk:
C : C
no increased risk of type 2 diabetes
C : G
increased risk of type 2 diabetes
G : G
increased risk of type 2 diabetes
allele associated with increased type 2 diabetes risk. The C allele is the
normal allele.
Genotype and type 2 diabetes risk:
C : C
no increased risk of type 2 diabetes
C : T
1.2x risk of type 1 diabetes
G : G
1.2x risk of type 1 diabetes
It has been shown that progression to type 2 diabetes can be avoided by changing one’s lifestyle. A variety of factors are important in the development of the disease – sedentary lifestyle, physical inactivity, smoking and alcohol consumption. Studies have shown that obesity is the most important risk factor – nearly 90% of diabetic patients develop type 2 diabetes mostly because of excess body weight.
Diet is also considered a risk factor. A low fiber diet with high glycemic index and total and saturated fat intake is associated with higher risk of type 2 diabetes. Frequent consumption of processed meat may also increase the risk.
People with one or two risk alleles in either or both markers should take some steps to lessen the risk of developing the disease:
- aim for at least 30 minutes of physical activity every day
- quit or reduce smoking quit or reduce the consumption of alcoholic beverages
- if you are overweight or obese, lose weight
- eat a healthy diet with enough fiber, lower glycemic load and less saturated fat, avoid excessive consumption of processed meat products
It is estimated that the onset of type 2 diabetes occurs several years (4-7) before the actual clinical diagnosis and many people already have organ damage at this point. Therefore, it is recommended that people with a risk factor (e.g. obesity) and/or risk allele undergo a screening test. Consulting with a physician is recommended.
https://link.springer.com/article/10.1007%2Fs00125-008-0973-4
http://diabetes.diabetesjournals.org/content/57/3/791.long
https://www.nature.com/articles/nrendo.2017.151
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3464757/
https://academic.oup.com/jcem/article/93/8/3136/2598804
The information provided in this article is based on published SNP (single nucleotide polymorphism) data and is for educational purposes only. Most published studies about genetic variants in the DNA explain only a small part of the heritability of a trait or disease risk, and often do not take into account how different variants may interact with each other. In addition, many published studies do not account for medical history or environmental, dietary, microbial, or lifestyle factors, which may alter true risk for any trait or disease.
The relevance of each article may vary based on ethnicity. Nothing in the genetic article should be used for medical self-diagnosis or self-treatment. The information provided should not be considered complete, nor should it be relied on to suggest diagnosis or treatment of a particular individual. You should always get the advice of your doctor or other appropriate health care professional if you have any questions about diagnosis, treatment, prevention, mitigation, or cure of any medical condition, phenotype, condition, impairment, or the status of your health.
ALLELE
An allele is a variant form of a gene that is located at a specific position, or genetic locus, on a specific chromosome. Humans have two alleles at each genetic locus, with one allele inherited from each parent.
CHROMOSOME
A chromosome is a thread-like structure of DNA that carries hereditary information, or genes. Human cells have 22 chromosome pairs plus two sex chromosomes, giving a total of 46 per cell.
DISEASE PREVALENCE
The proportion of individuals in a population having a disease or characteristic. Prevalence is a statistical concept referring to the number of cases of a disease that are present in a particular population at a given time, whereas incidence refers to the number of new cases that develop in a given period of time.
DNA
DNA, or deoxyribonucleic acid, is the main component of chromosomes and the carrier of genetic information in nearly all living organisms. DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C).
GENE
A hereditary unit consisting of a sequence of DNA that occupies a specific location on a chromosome. Genes are transferred from a parent to offspring, and are responsible for the physical and heritable characteristics or phenotype of an individual.
GENETIC VARIANT
An alteration in the most common DNA nucleotide sequence. The variant can be benign, pathogenic or of unknown significance. SNPs are the most common type of genetic variation.
GENOTYPE
The genetic makeup of an individual organism. It may also refer to just a particular gene or set of genes carried by an individual. The genotype determines the phenotype, or observable traits of the organism.
ODDS RATIO
The odds ratio is a way of comparing whether the odds of a certain outcome is the same for two different groups. In this report, the odds ratio estimates the probability of a condition occurring in a group of people with a certain genetic variant compared to a group of people without that variant.
An odds ratio of 1 means that the two groups are equally likely to develop the condition. An odds ratio higher than 1 means that the people with the genetic variant are more likely to develop the condition, while an odds ratio of less than 1 means that the the people with the variant are less likely to develop the condition.
PHENOTYPE
A description of an individual’s physical characteristics, including appearance, development and behaviour. The phenotype is determined by the individual’s genotype as well as environmental factors.
POPULATION ALLELE FREQUENCY
The allele frequency represents the incidence of a gene variant in a population. Alleles are variant forms of a gene that are located at the same position, or genetic locus, on a chromosome.
SNP
Single nucleotide polymorphisms, frequently called SNPs, are the most common type of genetic variation among people. A SNP is a variation in a single nucleotide that occurs at a specific position in the genome.
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