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Published on January 01, 2019

Many Type 1 Adults Misdiagnosed With Type 2 Diabetes

Type 1 diabetes long has been considered a disease that presents in childhood, while Type 2 diabetes is more prevalent in adults. However, Type 1 can develop in adults. Michelle L. Orr, MD, an endocrinologist with Meritas Health Endocrinology, calls on physicians to be vigilant when making a
definitive diagnosis.

Beyond Age

A study published in the Feb. 1, 2018, issue of The Lancet Diabetes & Endocrinology, examined the “Frequency and Phenotype of Type 1 Diabetes in the First Six Decades of Life: A Cross-Sectional, Genetically Stratified Survival Analysis From UK Biobank.” Researchers from the University of Exeter Medical School looked at 13,250 people diagnosed with Type 1 diabetes. They found 58% were diagnosed before age 30, but 42% were diagnosed between ages 31-60.

Type 1 symptom development is different in older adults. “Not every Type 1 is age 5-25,” Dr. Orr said. “Type 1 occurs in older ages. Mary Tyler Moore was diagnosed with Type 1 in her 30s. Symptoms in adults occur in a little bit slower fashion, so it’s not the dramatic illness we often see in children and adolescents, where they walk in very sick, nauseated, losing weight rapidly and urinating a lot.”

An elevated blood glucose level can be a telltale sign to start patients on diet, exercise and oral medicines for the treatment of Type 2. “There are a lot of new treatments for Type 2 diabetes, but it’s important before initiating any of those treatments that physicians determine if they are addressing Type 2 diabetes. This cannot be done based on age alone,” said Dr. Orr, adding that people who are not obese with a normal or lower body mass index can have Type 2 diabetes.

Type 2 Diabetes Medications

In addition to healthy eating, regular exercise and blood sugar monitoring, Dr. Orr looks to a number of treatment options, including:

  • Concentrated insulins, including U-200, U-300 and U-500, which provide longer-acting benefits and thus do not need to be administered twice a day
  • GLP-1 agonists, which improve blood sugar levels; not advised for people with poor kidney function
  • Noninsulin injectables, such as GFLP-1 agonists; these are not a first-line treatment, but can be used with oral diabetes medications and insulin therapy
  • Rapid-acting analogue insulins, which are given at mealtimes and to correct high blood sugar
  • SGLT2 inhibitors, which have been shown to have some cardiovascular benefits

“What we do with medications is 10-20% of the work,” Dr. Orr said. “What the patient does is 80%. The key is patient education and modification of diet and activity. We always tell our patients we have the easy job of telling them what to do, but they have the hard job.”


Dr. Orr advises physicians in doubt to order a glutamic acid decarboxylase antibody test. However, a negative GAD antibody result is not conclusive for Type 2, so she recommends looking at C-peptide levels. “If a patient has elevated C-peptide levels with negative GAD antibodies, the patient almost certainly has Type 2 diabetes,” Dr. Orr said. “Physicians should be cautious about that patient with a low C-peptide level and negative GAD antibodies because they may still be looking at Type 1.”

For Dr. Orr, it is vital to look at these patients. “Some of the medications we use to treat Type 2 diabetes can promote diabetic ketoacidosis in a patient with Type 1,” she said. “As practitioners, we want what’s best for our patients. A Type 1 diagnosis may not be on the mind of even the most intuitive physicians. If in doubt, do the testing.”

Michelle Orr, MDMichelle L. Orr, MD

Dr. Orr received her medical degree from the University of Missouri. She was a resident in internal medicine and anesthesiology at the University of Missouri. She also was a fellow in endocrinology and metabolism at the University of Kansas.