Type 1 Diabetes Overview
Diabetes has two main types: type 1 (T1D) and type 2 (T2D). T1D typically occurs in childhood but may develop in adults in their late 30s to early 40s and is characterized by autoimmune destruction of beta cells in the pancreas. They are less likely to be obese compared to T2D patients. Approximately one million Americans have T1D. The annual rate of new cases for children younger than 10 years is 19.7 per 100,000 and 18.6 per 100,000 population for 10 years or older.
The main risk factor of T1D is having a first-degree family member with T1D. Monozygotic twins have a 50% increased risk, siblings have 5-6% risk, people with positive maternal history have 2-3% risk, and positive paternal history have 5-6% risk. If both parents have T1D, the risk is almost 30%. It is most prevalent in Europeans, especially northern Europeans, and least prevalent in East Asians. Other risk factors include viral infections (enterovirus, mumps, rubella), exposure to cows’ milk in infancy, and increased maternal age during pregnancy.
Patients mostly present with polyuria (increased volume), polydipsia (excessive thirst), polyphagia (excessive hunger), and unexplained weight loss. They may experience lethargy, nausea, and blurry vision. A diagnosis can be made by measuring the plasma glucose level:
Fasting plasma glucose ≥ 126 mg/dL (7.0 mmol/L)
OR
2-hour plasma glucose level ≥ 200 mg/dL (11.1 mmol/L) during a 75 g oral glucose tolerance test (OGTT)
OR
Random plasma glucose ≥ 200 mg/dL (11.1 mmol/L)
The HbA1c assay can be used to diagnose T1D in suspected asymptomatic patients. Screening is recommended for individuals with a T1D first -degree relative ideally before 10 years old, and another follow-up screening during adolescence.
The patients’ role in diabetes is vital as glycemic control is important in reducing and delaying the rate of microvascular complications and future cardiovascular events. All patients are recommended to self-monitor, record blood glucose levels and adjust insulin levels accordingly. Exercise and diet is an important part of management. A professional dietitian can tailor a plan for each patient and provide advice on their daily caloric intake, recommended amounts of dietary carbohydrates, fat, and protein, and how to ration calories between meals.
Complications of T1D and T2D are similar. They develop sensory and autonomic neuropathy due to damage in the blood vessels that supply to the nerves. Wall thickening of the small arterioles and capillaries causes ischemic changes in the kidney, retina, brain, and peripheral nerves.
T1D is a condition that requires patience, compliance and discipline. With proper control, the risk of complications can be reduced, prevented, or delayed. Patient education is a must and physicians should ensure that patient care includes routine follow-up tests and referrals to specialists.
Bottom Line
- T1D typically starts in childhood and patients are usually not obese.
- Most important risk factor: first-degree relative with T1D.
- Classical presenting symptoms: polydipsia, polyuria, polyphagia, unexplained weight loss. Other symptoms include : nausea, lethargy, blurry vision.
- Patient education: blood sugar control – self-monitor, record levels, insulin adjustment. Management – exercise, diet, insulin.
- Multidisciplinary – primary care physician, podiatrist, ophthalmologist, and others.
[expand title=”References“]
Aathira R, Jain V. Advances in management of type 1 diabetes mellitus. World Journal of Diabetes. 2014; 5(5):689-696.
Borchers AT, Uibo R, Gershwin ME. The geoepidemiology of type 1 diabetes. Autoimmune Reviews. 2010; 9(5):A355-365.
Davies JL, Kawaguchi Y, Bennett ST et al. A genome-wide search for human type 1 diabetes susceptibility genes. Nature. 1994; 371(6493): 130-136.
Diabetes Epidemiology Research International Group. Geographic patterns of childhood insulin-dependent diabetes mellitus. Diabetes Epidemiology Research International Group. Diabetes. 1988; 37(8):1113-1119.
Guideline: Diagnosis and classification of diabetes mellitus. Diabetes Care. 2010; 33(1):S62-69.
International Expert Committee report on the role of the A1C assay in the diagnosis of diabetes. Diabetes Care. 2009; 32(7):1327-1334.
Paronen J, Knip M, Savilahti E Et al. Effect of cow’s milk exposure and maternal type 1 diabetes on cellular and humoral immunization to dietary insulin in infants at genetic risk for type 1 diabetes. Finnish Trial to Reduce IDDM in the Genetically at Risk Study Group. Diabetes. 2000; 49(10):1657-1665.
Redondo MJ, Jeffrey J, Fain PR, EIsenbarth GS, Orban T. Concordance for islet autoimmunity among monozygotic twins. New England Journal of Medicine. 2008; 359(26):2849-2850.
Romesh K. Type 1 Diabetes Mellitus. Medscape. URL Link Accessed on: 1/18/2017, 5:02pm.
Steck AK, Barriga KJ, Emery LM, Fiallo-Scharer RV, Gottlieb PA, Revers MJ. Secondary attack rate of type 1 diabetes in Colorado families. Diabetes Care. 2005; 28(2):296-300.
Vehik K, Beam CA, Mahon JL et al. Development of autoantibodies in the trialnet natural history study. Diabetes Care. 2011; 34(9):1897-1901.
Yeung WC, Rawlinson WD, Craig ME. Enterovirus infection and type 1 diabetes mellitus: a systemic review and meta-analysis of observational molecular studies. British Journal of Medicine. 2011; 342:d35.
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