Type 1 Diabetes
Diabetes is a disease in which blood glucose levels are too high. In type 1 diabetes (T1D), the immune system attacks and destroys pancreatic beta cells that make insulin — a hormone that tells cells to absorb and use glucose for energy. T1D usually begins during childhood or adolescence, but it can occur at any age. The prevalence of T1D tends to increase as you travel away from the equator, with rates substantially greater in Finland and other Northern European nations than in China and Venezuela.
The signs and symptoms of T1D overlap with those of type 2 diabetes (T2D), which commonly results in many adults with T1D being mistakenly diagnosed with T2D. A classical sign of T1D is unintentional weight loss; other symptoms include:
- Increased thirst
- Extreme hunger
- Frequent urination
- Fatigue and weakness
- Blurred vision
- Impaired wound healing
Sometimes the first indication of T1D is a life-threatening condition called diabetic ketoacidosis (DKA), which is characterized by excessively high levels of ketone bodies in combination with high blood glucose. Symptoms of DKA include fruity-smelling breath, deep and rapid breathing, dry or flushed skin, and nausea or vomiting.
Like T2D, T1D is diagnosed using blood tests to assess plasma glucose levels. A fasting plasma glucose, 2-hour plasma glucose during a 75-gram oral glucose tolerance test, or HbA1c value can be used to diagnose T1D. To differentiate T1D from T2D, a blood test is used to detect the presence of two or more autoantibodies, namely autoantibodies to insulin, glutamic acid decarboxylase, islet antigen 2, or zinc transport 8.
Because the hallmark of T1D is insulin deficiency, the main medical treatment is multiple daily injections of prandial (i.e., with meals) and basal (i.e., background or between meals) insulin or continuous subcutaneous insulin infusion. There are multiple approaches to insulin treatment, but in general, some form of insulin is given in a planned regimen tailored to the individual's unique situation to prevent DKA and avoid severe hypoglycemia while meeting their glycemic targets.
In addition, adjunctive therapies to augment insulin treatment are being studied to optimize glycemic control. Pramlintide (an amylin analog) is the only option approved for use, but evidence from clinical trials suggests that common medications such as glucagon-like peptide-1 receptor agonists may also provide benefits.
Supplements have not been studied for treating T1D, specifically, but for improving glycemic control or helping to maintain healthy blood glucose levels in general. A variety of micronutrients have been examined, most notably zinc, selenium, chromium, vitamin D, vitamin B3, and vitamin C. Other common supplements marketed to improve glycemic control include dietary fiber, probiotics, cinnamon, aloe vera, and panax ginseng.
Nutrition — especially carbohydrates — has a substantial effect on blood glucose levels, so it’s important for people with T1D to plan their meals and corresponding insulin doses accordingly to optimize glycemic control. There is currently insufficient evidence to support one dietary pattern over another for managing T1D. Consequently, the eating plan should be individualized based on personal preferences, socioeconomic status, and comorbidities, with the goal of achieving individual glycemic, cardiovascular, and body weight goals and preventing disease complications. Additionally, eating plans should revolve around principles common among healthy dietary patterns, such as emphasizing nonstarchy vegetables, minimizing added sugars and refined grains, and choosing whole foods over ultraprocessed foods.
People with T1D should ideally perform at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity aerobic activity per week and 2–3 resistance exercise sessions, with no more than two consecutive days without activity to increase insulin sensitivity and lower the risk of cardiovascular disease.
The glycemic response to exercise is highly variable and is affected by baseline fitness status; the type, intensity, and duration of exercise; the amount of insulin in circulation; preexercise blood glucose level; and preexercise meal composition. As such, special care needs to be taken with respect to carbohydrate intake and insulin delivery around exercise to prevent hypoglycemia.
Although known to be an autoimmune disease, the precise triggers of T1D are largely unknown but genetic susceptibility and environmental factors both contribute to the development of the disease. The most significant contributor to genetic risk is the presence of certain HLA alleles, but other genes contribute to heritability as well. The research on environmental factors is comparatively less clear, but exposure to certain viruses (e.g., human enterovirus B), dietary factors (e.g., unsaturated fat, cow’s milk, vitamin D), and gut microbiota composition have all been associated with either a higher or lower risk of T1D.