DM Full Guideline (2010) - VA/DoD Clinical Practice Guidelines Home

Version 4.0
G. Determine and Document If Diabetes Mellitus Is Type 1 or 2
OBJECTIVE
VA/DoD Clinical Practice Guideline
for the Management of Diabetes Mellitus
Determine if insulin is a necessary component of treatment for the particular patient.
ANNOTATION
Patients with type 1 DM are insulinopenic (i.e., virtually absent insulin secretion), often due to autoimmune or toxic
(e.g., alcohol) destruction of the pancreatic beta cells. Patients with type 2 DM have underlying insulin resistance
and relative insulin deficiency.
Patients with type 1 DM may initially present with diabetic ketoacidosis (DKA). However it is not uncommon for
these patients to present to primary care with hyperglycemia alone, without symptoms of ketoacidosis.
In a primary care setting, the patient's age at the time diabetes is diagnosed, plus the BMI and level of urinary
ketones, and autoimmune markers are usually sufficient to classify the type of DM. In case of uncertainty a
consultation with specialty care may be considered.
Table D4. Clinical Classification of DM
Likely Type 1 Indeterminate Likely Type 2
Age < 30 years 30 - 40 years >40 years
BMI < 25 BMI* 25 - 27 >27
Urinary ketones Moderate to large Low to moderate None to low
*For Asian/Pacific Islanders the BMI threshold should be 23.
The increasing prevalence of obesity has translated to an earlier onset for type 2 DM. Therefore, using age alone as
a discriminator for the diagnosis of type 1 or type 2 DM may be misleading.
DISCUSSION
Because patients with type 2 or initially indeterminate DM (sometimes referred to as “atypical”, “ketosis-prone”, or
“Flatbush” diabetes) can present with ketoacidosis (especially with concomitant alcohol use) they should be
reevaluated after stabilization to assess continued need for insulin therapy.
Patients with type 1 DM require insulin and will develop ketoacidosis if not treated with insulin or if insulin
requirement increases during stress. Patients with type 1 DM are generally more prone to develop hypoglycemia or
ketosis, especially during times of stress.
Patients with type 2 DM may need to be treated with insulin to improve glycemic control but will not usually
develop ketoacidosis if they do not receive insulin. Patients with DM adequately treated with medical nutritional
therapy (MNT), physical activity, oral agents, and/or injectable GLP-1 agonists or amylin analogs are classified as
having type 2 DM.
Diagnosis of Type 1 versus Type 2 diabetes in adults presenting with ketoacidosis is challenging, especially in noncaucasian
patients. Studies with good representation of Hispanics and African Americans find as many as ~50%
with ketoacidosis have Type 2 DM and many can eventually be weaned of insulin. Also, patients with a history of
thyroid or other autoimmune disease and patients without a family history of Type 2 diabetes are more likely to have
Type 1 diabetes.
Module D: Core Page 20