Diabetes Diagnosis: Which One (or Two) Is It?
As a diabetes educator and Children's National Medical Center physician, I often meet with individuals outside my usual role as healthcare provider. It was in this unique situation that I found myself meeting with a lovely gentleman who had literally "purchased" my consultative time during the silent auction at The Oktoberfest fundraiser held at the Old Angler's Inn in Potomac, Maryland. He wanted to meet me for dinner to discuss his diagnosis of diabetes. During dinner, while discussing his medical history, it became apparent that he was unsure of just what kind of diabetes from which he was suffering. I was determined to investigate. I have written several blogs about how to diagnose diabetes and the different kinds of diabetes. In this situation, however, I truly realized the frustration, suffering, and confusion endured when someone is unaware of his or her true diagnosis. Sometimes, we are unable to diagnose precisely the type of diabetes; but in many instances, we can at least limit the number of possibilities by both laboratory testing and clinical observation.
After the diagnosis of diabetes is confirmed, I then decide if the diabetes is insulin or non-insulin dependant. Sometimes, I may start insulin immediately (to eliminate glucose toxicity), even if I decide that the newly diagnosed type of diabetes may ultimately turn out to not be insulin dependant. If I determine that the child or young adult has insulin dependant diabetes it usually is either type 1 autoimmune diabetes, type 1 idiopathic in nature (i.e., cause unknown), steroid or medication induced diabetes, or cystic fibrosis related diabetes (CFRD).
If I determine that insulin is not required for survival, I am generally thinking of either type 1.5 diabetes, type 2 diabetes, or a genetic form of diabetes identified as Maturity Diabetes Onset of the Young (MODY). In neonates with hyperglycemia, a genetic form of Diabetes: Permanent Neonatal Diabetes must be ruled out as well, which may be treated with oral medication.
What are the physical and laboratory characteristics typically associated with insulin dependant or type 1 diabetes?
- Generally a patient with new onset type 1 diabetes is thin and has symptoms of increased drinking, increased urination, increased appetite, and has lost weight.
- Individuals with type 1 diabetes may present with diabetic ketoacidosis secondary to lack of insulin production.
- Type 1 patients need insulin to survive. (Oral medications may increase insulin sensitivity; but will not be sufficient to sustain survival).
- C-peptide (a marker of insulin) is not detected in the blood. (The exception is the honeymoon period when the body pulses out insulin from the remaining live pancreatic beta cells.)
- GAD-65 antibodies (and others) may be present in autoimmune type 1 diabetes (though not always).
- After the honeymoon period, blood sugars fluctuate a bit more than in type 2 diabetes.
- In some cases, there is a family history of autoimmune diseases (Celiac, Hashimoto's Thyroiditis, Graves Disease, or Addison's Disease <adrenal insufficiency>).
- In many cases, there is no family history of type 1 diabetes.
What are the physical and laboratory characteristics associated with Non-insulin dependant diabetes? (Type 2, MODY)
- There may be physical evidence of darkened velvety areas of skin in intradigenous areas (arm pits, neck, thighs etc.) called acanthosis nigricans typically in patients with T2DM.
- Obesity may be present in association with the metabolic syndrome.
- The individual may be thin especially in MODY.
- All ethnic backgrounds are affected; however type 2 diabetes tends to run in families of Latino, African American, Native American Indian, and Pacific Islander background.
- Insulin is usually present. Therefore, c-peptide is present in the blood. (However, after many years with type 2 diabetes, the natural history is such that endogenous insulin production is often lost).
- GAD-65 antibodies are usually not present. However, in the form of type 1.5 diabetes (a combination of characteristics of type 1 and type 2 diabetes), antipancreatic antibodies may, indeed, be present.
- Individuals with MODY often physically look like type 1 patients, but at times behave more like Type 2 patients. They may require insulin at times or none at all. MODY is usually referred to as "monogenic diabetes" and is caused by mutations in autosomal dominant genes. Insulin production is often hampered or ineffective. Most commonly, MODY resembles mild type 2 (or in some cases-mild type 1) with some insulin production and normal insulin sensitivity. The most common types of MODY are type 2 and 3.
- Patients with well-controlled type 2 diabetes or MODY are more likely to have hb A1cs well below 6.0 percent with blood sugars in a tightly controlled range (minimal fluctuation).
The individual above was thin, presented with hyperglycemia as a young adult, and was immediately presumed to have type 2 diabetes. He initially began with oral medication and over the last 10 years has had extremely well controlled blood sugars both on and off an insulin sensitizer. No insulin was required. He did not know results of any laboratory work that was performed initially and finally decided to find out what form of diabetes he had. As MODY may make up approximately 5 percent of presumed type 1 or type 2 diabetes cases in a large clinical cohort, it was imperative for us to consider this diagnosis. In addition, since the inheritance is autosomal dominant, it is vital to know this key information in terms of family planning and risk to subsequent children. Diagnosis of MODY may be made by DNA analysis from serum samples searching for specific gene mutations. Treatment is usually begun with oral sulfonylureas.
Laboratory results are pending at this time.