How to diagnose Type 1 diabetes? Are there any Type 1 diabetes tests?
The diagnosis of type 1 diabetes is primarily based on clinical features and elevated blood glucose levels. Patients with Type 1 diabetes typically have marked elevation in blood glucose level, which are usually more than 200 mg/dl at the time of diagnosis. These patients also experience dramatic symptoms due to marked elevation in blood glucose levels. These symptoms are: excessive thirst, excessive urination, weight loss, fatigue, and occasionally diabetic ketoacidosis (DKA.)
1. Fasting Blood Glucose
Usually this is done as part of a routine blood test after you have fasted overnight.
A Fasting Blood Glucose greater than 125 mg/dl = Diabetes.
2. Hemoglobin A1c ( HBA1C)
Hemoglobin A1c is another blood test for the diagnosis of diabetes. Hemoglobin A1 C above 6.5% clinches the diagnosis of diabetes.
Do You Have Type 1 Diabetes?
Once you are diagnosed with diabetes, the next important question is: what type of diabetes do you have – type 1 or type 2.
Clinical Diagnosis of Type 1 Diabetes
You Are Probably a Type 1 Diabetic If:
- You have been on insulin ever since the diagnosis of your diabetes or shortly thereafter (although sometimes your physician may erroneously place you on insulin even though you are a Type 2 diabetic)
- You are on relatively small doses of insulin (usually less than 40 units/day)
- You are thin
- You do not have a family history of diabetes
- You do not have high triglycerides and low HDL cholesterol
- You do not have high blood pressure
Age Has No Bearing on Your Type of Diabetes
In the past, we erroneously used to classify Type 1 diabetes as “Juvenile Onset Diabetes” and Type 2 diabetes as “Adult Onset” or “Maturity Onset.” But then we realized that many young people were actually not Type 1 but Type 2. As a matter of fact, Type 2 diabetes among teenagers is increasing at an alarming rate, thanks to our culture of fast food and a sedentary lifestyle.
Type 1 diabetes can rarely develop in adults. Therefore, now we use the terms Type 1 or Type 2 and don’t use the previous, age-related categories. Sadly, I see some physicians still using the old terms. Presuming someone has Type 1 diabetes based upon their young age can be very misleading.
Blood Tests to diagnose Type 1 Diabetes
There is a special blood test that can help categorize whether a person is Type 1 or Type 2. This blood test is known as C-peptide, which is a hormone produced by the pancreas in conjunction with insulin.
The blood test for C-peptide should be done one hour after a meal.
Almost all Type 2 diabetic patients have some production of insulin and C-peptide. Actually, many Type 2 diabetics have excessive production of insulin and an elevated level of C-peptide. In contrast, most Type 1 diabetics have no insulin production and, therefore, no C-peptide in their blood.
Rarely, and only in small quantities, is C-peptide detectable in the early stages of Type 1 diabetes. In these difficult cases, further blood testing, such as anti-islet cell antibodies or anti-GAD antibodies, can be carried out. These antibodies are present in most Type 1 diabetic patients.