Is This Patient Type 1 or Type 2? A Real Mystery!

The Patient:

Kyle is a 32-year-old male who was recently diagnosed with type 2 diabetes last week by his PCP and put on metformin. Upon questioning Kyle at our first appointment, he did not feel too badly, but he had kind of lost his appetite and was feeling a little lethargic. However, he was still working full-time as a rocket scientist (yes really). He was more thirsty than usual and peeing more frequently (once or twice a night). He also has lost 40 pounds in the last year, but he did not think much of it as he started out heavy (238 lbs) and chalked it up to moving to Texas (which came with a different lifestyle). All of his symptoms seemed to be getting worse over the past few months. Kyle has no other medical problems and was not taking any medications at the time of his diagnosis.

Kyle does have a family history of type 2 diabetes and obesity. His maternal grandmother and grandfather have type 2 diabetes, and neither is treated with insulin. There’s no other known type 1 or type 2 diabetes on either side of the family.

The Initial Lab Tests:

Kyle’s laboratory data showed mostly normal values, except for a glucose of 273 mg/dL and an A1c of 12%, indicating his average blood glucose level was well over 200 mg/dL. His triglycerides were 74 mg/dL. (This will be important later in the discussion. His HDL was 36 mg/dL and his LDL was 146 mg/dL).

In addition, his C-peptide, which is a measurement of insulin production by his pancreas, was normal, as was his insulin level. He did have a test for two of the four islet autoantibodies that are present in people who have type 1 diabetes. His GAD65 autoantibody was negative (normal) but very surprisingly, his Zinc Transporter (ZnT8) was 65 U/mL (a normal result is less than 15 U/mL).

Over the past few weeks he has tried to cut back on his carbohydrates, and noted his finger stick values were much better – mostly below 200 mg/dL with some as low as 106 mg/dL.

The Big Question…Is It Type 1 or Type 2?

Kyle is a very interesting patient, and not unlike lots of people with diabetes we see in clinic who have features of both type 1 and type 2 diabetes. At first, being overweight without too many symptoms (especially with an A1c of 12%) and a family history of type 2 diabetes, his PCP treated him with a very common type 2 medication (metformin). Kyle was also started on an ACE inhibitor to keep his blood pressure at goal and protect his kidneys, as well as a statin to lower his LDL cholesterol).

The fact that he lost 40 lbs tells me he really was insulinopenic (not enough insulin in his body), which leads to the breakdown of fatty tissue used for energy when insulin levels are low. Even though his C-peptide level and insulin levels were “normal” on the lab test, they were very low considering his glucose level was 273 mg/dL. Because his blood sugar was so high, his insulin levels should have been much higher also, indicating that his pancreas isn’t secreting enough insulin. If you’re reading this case, you can now be an honorary endocrinologist!

In terms of more type 1 features, he does have a positive islet autoantibody (Zinc Transporter) commonly seen in people who have type 1 diabetes and not type 2. Lastly, his triglyceride levels are very normal, and in people with type 2 diabetes with high glucose levels, the triglyceride levels are commonly super high with normal or low LDL levels. Kyle’s LDL level was elevated.

So there you have it, lay endocrinologists of America (L.E.A.). It is important to find out if Kyle has type 1 or type 2 diabetes for therapeutic and genetic reasons. Approaches to therapy will be very different depending on what type of diabetes he has, as will the screening for diabetes in his three kids and other first- and second-degree relatives.

The Plan for Now:

1. Get a CGM ASAP and start monitoring Kyle during his normal daily activities.
2. Start basal and fast-acting insulin if needed, based on his glucose values.
3. Order all four of the islet autoantibody tests to see if others are positive, putting him in the type 1 category. (The ADA now classifies having two or more of these autoantibodies as early stage T1D).
4. Measure other autoimmune labs, testing for celiac and autoimmune thyroid disease, also associated with T1D.
5. Get more information on the details of his family members with diabetes (age of diagnosis, what they were treated with and degree of obesity)
6. Have Kyle look at the information in our video vault to get knowledgeable on exercise and good dietary habits.

What do you think Kyle’s diagnosis will be?

Click Below for an Update on Kyle’s Case: