Know the Dos and Don’ts of Type 1 Diabetes Coding
Make sure you add these 2025 ICD-10 code updates to your list. There’s a lot of room for error when you code patients with type 1 diabetes. From making sure you don’t confuse codes for the different types of diabetes to making sure you include the code for long-term insulin use, there are a lot of moving parts in type 1 coding that you need to understand. So, here are four things you should be doing — and three that you shouldn’t — to make sure you are keeping everything straight. Do Understand Diabetes Types Altogether, ICD-10 identifies five different diabetes diagnosis code groups, which you should familiarize yourself with: For the most part, you will rarely, if ever, use the combination codes E08.-, E09.-, or E13.- to code diabetes when it is a secondary condition. Instead, you’ll pretty much confine yourself to diagnoses in the E10.- and E11.- categories. Here, it is important to remember that type 1 diabetes denotes insulin dependence, where the body makes no insulin; whereas type 2 diabetes denotes insulin resistance, where the body produces insulin, but of an insufficient quality or quantity. Don’t Let Age Determine Diagnosis To properly code type 1 diabetes, you next need to learn how to interpret the ICD-10-CM guidelines specific to it. The first of them, I.C.4.1, tells you: “The age of a patient is not the sole determining factor, though most type 1 diabetics develop the condition before reaching puberty. For this reason, type 1 diabetes mellitus is also referred to as juvenile diabetes.” In other words, a pediatric diabetic patient should not automatically be coded to E10.- because of their age. In fact, the chances of a pediatric patient developing type 2 diabetes are much greater now than they have ever been, and “in some regions in the United States, type 2 diabetes mellitus is as frequent as type 1 diabetes mellitus in adolescents,” according to Thomas Reinehr in an article in the World Journal of Diabetes. Don’t Automatically Default to E11.- Another guideline that can be as confusing as I.C.4.1 is I.C.4.2, which tells you “If the type of diabetes mellitus is not documented in the medical record the default is E11.-, Type 2 diabetes mellitus.” The consequences of following this guideline blindly can potentially be very problematic because “if your patients have type 1 diabetes, their care will be much more complex, and this will not be supported if the diagnosis doesn’t match the treatment,” says Marcella Bucknam, CPC, CCS-P, COC, CCS, CPC-P, CPC-I, CCC, COBGC, revenue cycle analyst with Klickitat Valley Health in Goldendale, Washington. This means “treatments may not be paid, because physician payment is becoming increasingly value-based and payments are risk-adjusted based on patient conditions,” according to Bucknam. So, it is vitally important that you work with your pediatrician to arrive at the most specific diabetes diagnosis possible for your patient. Do Code for Complications and Control The next step in coding type 1 diabetes is to look at any complications resulting from the condition, which include degrees of diabetes control. You can code these with the following 4th character E10 subdivisions (which are the same for E11): Control is indicated as a complication in the 4th and 5th characters: E10.64 (Type 1 diabetes mellitus with hypoglycemia) when the patient’s blood sugar levels are below 70 mg/dL), and E10.65 (Type 1 diabetes mellitus with hyperglycemia), when the patient’s blood sugar levels are above 130 mg/dL. Another 4th character, 9, indicates that the condition is controlled (e.g. E10.9 (Type 1 diabetes mellitus without complications)). But using 9 “should be the exception rather than the rule, given that most people with diabetes have either suboptimal control, complications, or both,” according to Joy Dugan and Jay Shubrook, authors of “International Classification of Diseases-10 Coding for Diabetes.” Do Code for Insulin Use As all type 1 diabetics are insulin-dependent, you should keep Z79.4 (Long term (current) use of insulin) at your fingertips when coding diabetic patients. Per guideline I.C.21.c.3, you assign Z79.4 if the patient is taking a drug over an extended period (“long-term”) for a chronic condition, and the patient is taking the medication at the time of the encounter (“current”). Do Code for Comorbities and Associated Conditions Comorbid and associated conditions are very common for diabetes patients, and even though many of the type 1 diabetes codes are combination codes, you should follow the Use additional code instructions scattered throughout the E10.- codes, including the ones concerning L97.- (Non-pressure chronic ulcer of lower limb, not elsewhere classified). You should also have the following codes and code groups at your fingertips: Don’t Forget These New Codes Beginning Oct. 1, 2024, ICD-10-CM introduced the following new codes under parent code E10.A- (Type 1 diabetes mellitus, presymptomatic): According to AHA Coding Clinic for ICD-10-CM(2024 Vol. 11, No. 4), presymptomatic type 1 diabetes “consists of the presence of islet autoantibodies or biomarkers that attack islet autoantigens, such as insulin-producing beta cells in the pancreas.” These islet autoantibodies “are useful in predicting the development of T1D mellitus.” You’ll use E10.A1 when the patient has “multiple islet autoantibodies with normoglycemia” and E10.A2 when the patient “has one or more islet autoantibodies with dysglycemia,” according to Coding Clinic. ICD-10-CM 2025 also made additions to the hypoglycemia codes. You’ll now use the following in addition to E10.64 (Type 1 diabetes mellitus with hypoglycemia) per the Use additional code instruction for E10.64: Bruce Pegg, BA, MA, CPC, CFPC, Managing Editor, AAPC
