Did you know DNA can influence how much insulin is released into your blood?
From pig pancreases to bacteria that make human proteins: Insulin and the risk of type 2 diabetes
In 1923, the first commercially-produced insulin became available. Trains would bring containers packed with cow (and later pig) pancreases to Indianapolis. Here, Eli Lilly (the first company to mass produce insulin), processed more than two tons of pancreases to produce a mere 8-ounce vial of insulin. This is how life-saving insulin was predominantly produced for many years, until the first synthetic ‘human’ insulin became available in 1982. The discovery and mass production of insulin changed diabetes from a death sentence to a condition with very little effect on life expectancy.
Diabetes is a disease characterized by reduced insulin production and/or a reduced response to insulin. Our bodies are like machines, they run on food for fuel. When we mow down a lasagna, the meat, cheese and the pasta noodles are broken down into proteins, fats and sugars, all components that can be used to generate energy. Some of it is used immediately, but the bulk is stored in our tissues. Insulin is the key hormone for storing sugars for later use (in the form of glycogen). Making a hormone from scratch takes a considerable amount of time. Hence, insulin is made ahead of time and stored in the pancreas until required. Glucose (the primary sugar found in our blood) stimulates the release of insulin, which then signals for glucose to be taken up into muscle, liver and fat cells.
However, if not enough insulin is produced and/or released from the beta cells in the pancreas, or the body doesn’t respond to the available insulin, the risk of diabetes is significantly increased. Type 1 diabetes is a rare disorder that occurs when the body can’t produce its own insulin. Type 2 diabetes is a lot more common, and although many type 2 diabetics can produce insulin, their cells become resistant to the signals of the insulin molecule.
Type 2 diabetes has a strong genetic component. To date the TCF7L2 gene is one of the best predictors of type 2 diabetes risk. The TCF7L2 protein turns on several other genes, some of which have a role in insulin secretion. The rs7903146 and rs12255372 variants of TCF7L2 gene are linked to elevated type 2 diabetes risk. People who inherit the rs7903146 version make five times more TCF7L2 protein, and are at much higher risk of developing diabetes. In the presence of glucose, they only release half as much insulin compared to people with the normal version of the gene. Adding insult to injury these individuals also have reduced levels of the incretins that also participate in lowering blood sugar levels.
The HNF4A protein also turns on other genes in our body, including ones involved in insulin production. The rs1800961 version of HNF4A lowers protein activity, and is also linked to an increased risk of type 2 diabetes.
The availability of artificial insulin has allowed us to leave behind the days where a minimalist diet was the only way to prolong the life of a diabetic. But unfortunately it is far from a cure. Maybe one day we will have a cure, if scientists can devise a way to create beta cells to produce insulin, just like the normal beta cells in a healthy individual.