Type 1 Diabetes and LADA
Type 1 diabetes, formerly known as juvenile diabetes and as insulin-dependent diabetes, is what many people think of as real diabetes. The familiar image is one of an exceptionally thin child taking insulin injections, and that’s a fairly accurate image.
Type 1 diabetes does tend to occur at a younger age, and insulin injections are a routine part of having type 1 diabetes. Type 1 is relatively rare compared to type 2, accounting for less than 10 percent of diabetes cases worldwide.
Type 1 diabetes also commonly shows itself suddenly, frequently diagnosed only following a life-threatening emergency as the capacity to produce insulin is lost. In retrospect, the signs of type 1 diabetes mellitus — constantly flowing sweet urine along with an unquenchable thirst and a never ending appetite — would have been obvious for weeks. Still, an onset with symptoms building for a week or a month is far more acute than the onset of type 2 diabetes.
Losing the capacity to produce insulin
Your immune system protects your body’s internal workings from intruders, whether the intruder is a splinter or a disease causing virus or bacteria. Your immune system can mobilize blood cells immediately with names like killer T-cells and begin manufacturing antibodies specifically designed to target the intruder and finish the job over a period of a few days. Your immune system has probably saved your life many times.
Sometimes, because an intruder contains substances in common with body tissue, this awesome firepower is directed both at an intruder and also at essential parts of the same body the immune system is supposed to protect.
When damage is caused by one’s own misguided immune system, the condition is called an autoimmune disorder. In rheumatoid arthritis, for example, the immune system attacks and damages certain tissue in joints, deforming fingers as a result.
In type 1 diabetes a confused immune system attacks and destroys the insulin producing beta cells of the pancreas. The destruction of pancreatic beta cells means that eventually no insulin is naturally produced, and the body can’t move glucose into cells.
That typical sudden and violent onset of type 1 diabetes is not quite as sudden as it seems. The emergency is actually the climax to beta cell destruction that progresses over a period of weeks or months as insulin-producing capacity is steadily depleted.
Cells begin to starve for glucose fuel, even as blood glucose levels go higher. Sensing that cells need glucose, hunger hormones stimulate appetite, but additional food only sends blood glucose higher again.
Eventually, as blood glucose levels rise to many times normal levels, dehydration from excreting glucose constantly in urine and a buildup of waste products called ketones from cells burning fat (an emergency alternative to glucose) cause a condition known as diabetic ketoacidosis (DKA).
DKA is an urgent medical emergency, and this first DKA event begins what is for all intents and purposes a lifetime of daily insulin injections necessary for survival.
The major practical difference between type 1 and type 2 diabetes mellitus is the universal requirement for insulin, by injection or some other method, in type 1 diabetes. Patients with type 2 diabetes usually do not require insulin at the beginning of their illness.
Prior to the mid 1920s when insulin was first isolated, people with type 1 diabetes simply didn’t survive. Now, however, medical advances in insulin quality, insulin delivery systems (insulin pumps), and real-time blood glucose monitoring allow people with type 1 diabetes to effectively control blood glucose levels for a lifetime.
Latent autoimmune diabetes of adults (LADA) has more in common at the start with type 2 diabetes than with type 1 diabetes with one key exception: a berserk immune system.
LADA does not come on dramatically like typical type 1 diabetes. In fact, diagnosis and treatment almost always begins as if the patient has developed type 2 diabetes, which doesn’t involve autoimmune destruction of beta cells. DKA doesn’t typically occur, insulin therapy is not required, and oral medications with lifestyle changes can often manage blood glucose levels effectively for a time.
LADA is so different from type 1 in these regards that some call LADA type 1.5 diabetes. However, what puts LADA in the type 1 diabetes category is the presence of beta cell antibodies, and the resulting destruction of these insulin producing cells, albeit ever so slowly.
Adults with LADA tend to require insulin therapy for blood glucose control sooner than adults with type 2 diabetes, and antibody studies of patients diagnosed as type 2 suggest that more than 10 percent (in some studies nearly 30 percent) are LADA instead.
Puzzling over the causes of type 1
The primary cause of type 1 diabetes is clear — destruction of insulin producing beta cells by the patient’s own immune system. The cause of this misguided immune system response is not clear.
There is a genetic component that increases the risk for developing type 1 diabetes, but studies of identical twins, who are literally identical in a genetic sense, demonstrate that genetics doesn’t cause type 1 diabetes. Having an identical twin with type 1 diabetes increases the twin’s risk of developing type 1 diabetes only to something like 30 percent.
Certain viral infections seem to be a promising suspect in triggering the autoimmune response, but there is no smoking gun. Some researchers have proposed that type 1 and type 2 diabetes are essentially the same disease expressed in different ways.
Population data hints that inadequate vitamin D is to blame, that persistent organic pollutants like dioxin might play a role, or that excessive hygiene has contributed to an overactive immune system.
The bottom line is that the cause or causes of the autoimmune response leading to type 1 diabetes is still unknown at this time.