What is insulin? Learn how DNA can contribute to certain types of diabetes
It’s a delicate relationship we have with sugar. On the one hand, sugars are full of energy that our bodies need (in fact, our brains get energy almost exclusively from it). But too much sugar coursing through our veins can wreak havoc. To help us mine sugars for energy safely, our bodies rely on the insulin gene, INS.
Insulin’s job is simple: get cells to open their sugar gates. Every cell in our body is surrounded by a protective membrane that separates the inside of a cell from the outside environment. Among its many benefits, one big effect of having a membrane like this is that cells can be selective about what they bring into the interior of a cell, and what is denied entry. In service of this, a cell’s membrane will be garrisoned with multiple proteins that act like a gated pore, capable of opening and closing to control the entry of specific molecules. It is through gates like this that hormones like insulin are able to control how much sugar enters a cell.
When there is too much sugar in the blood, it can cause a multitude of problems1. Because of this, our body has devised a way to monitor blood sugar levels and dispatch insulin when necessary to help control it. After eating carbohydrates, our blood sugar spikes. That’s not entirely bad because it means our body is being flooded with potentially useful, energy-rich sugars. But to get use out of them, cells need to know that sugar is there and that they need to open their sugar gates.
This is where the pancreas comes into play. The pancreas is a specialized organ that produces sugar-related hormones. When blood sugar levels are too low, the pancreas releases a hormone that tells cells in our body to liberate their sugar stores so that other cells can use them. Similarly, when the body has too much sugar, the pancreas releases insulin to tell cells that they need to bring sugar in from the blood2.
Many people have heard of insulin because of its role in diabetes. Diabetes is a condition where the body loses its ability to regulate blood sugar levels. In Type 1 diabetes, this often happens because a person’s body has mistakenly destroyed the insulin-producing cells in the pancreas. Type 2 diabetes typically develops when a person’s cells are less sensitive to sugar or insulin, meaning they’re less able to bring blood sugar levels down.
Genetic testing for MODY
- There are a few situations where you may consider genetic testing for MODY:
- You have a family history of diabetes, especially involving the types described below;
- Any members of your family have received a MODY diagnosis;
- You’ve been diagnosed with Type 1 diabetes with abnormal blood results (that is, your bloodwork has a lack of autoimmune markers—some doctors will refer to this as “atypical Type 1 diabetes”); or
- You’ve been diagnosed with Type 2 diabetes but have a low to normal body mass index (BMI).
A less well-known form of diabetes is known as maturity onset diabetes of the young (MODY). This type of diabetes is usually caused by variants in the DNA that disrupt a gene critically involved in sugar regulation. Currently, there are about 14 genes known to be associated with MODY3. One such gene is the INS gene. A few variants have been found in INS that prevent the body from getting full use out of it5. Without a properly working insulin gene, sugar regulation goes awry.
It’s estimated that less than 1% of MODY cases are due to one or more variants in the INS gene3-5. These cases—and this is true for MODY in general—have often gone undiagnosed, instead being classified as either Type 1 or Type 2 diabetes. This is because MODY looks a lot like the other forms of diabetes, and the only way to properly diagnose someone with MODY is through DNA testing. Medical guidelines for treatment can be different depending on the type of diabetes a person has, so it’s important to know if it’s MODY, Type 1, or Type 2. Fortunately, many people diagnosed with MODY have the potential to stop taking insulin and instead begin a treatment regimen that’s tailored to their specific form of diabetes3,4. This isn’t true in every case, and no decisions about treatment should be made without consulting a physician. In the case of MODY caused by variants in the INS gene, insulin injections may still be necessary4.
2Pandol, Stephen J. “Introduction.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, 1 Jan. 1970, www.ncbi.nlm.nih.gov/books/NBK54131/.
3Naylor, Rochelle. “Maturity-Onset Diabetes of the Young Overview.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, 24 May 2018, www.ncbi.nlm.nih.gov/books/NBK500456/.
4“Maturity-Onset Diabetes of the Young: What Do Clinicians Need to Know?” Diabetes & metabolism journal vol. 39,6 (2015): 468-77.
5Boesgaard, Trine W et al. “Further evidence that mutations in INS can be a rare cause of Maturity-Onset Diabetes of the Young (MODY)” BMC medical genetics vol. 11 42. 12 Mar. 2010, doi:10.1186/1471-2350-11-42