Secondary Diabetes Mellitus Coding

With the epidemic of diabetes in the U.S. and more Americans being diagnosed with the condition than ever before, the need for more specific diagnosis codes to represent the various forms of the disease has significantly increased. In 2008, 20 new diagnosis codes were released to track secondary diabetes, defined as a diabetic condition whose underlying cause is not genetics or environmental conditions.

Coders are required to determine the specific manifestation of the disease (e.g., diabetic nephropathy, retinopathy, ketoacidosis, etc.), whether it is considered to be in a controlled or uncontrolled state, and also the underlying etiology of the disease. This will require medical staff education on the need for specific documentation related to diabetes causes. In addition, coding staff and physicians should prepare for much more specificity in diabetes coding after implementation of ICD-10-CM.

The ICD-9-CM secondary diagnosis codes are as follows:



249.00 — 249.01

Secondary diabetes mellitus w/o mention of complication, [not stated as uncontrolled, or unspecified/uncontrolled]

249.10 — 249.11

Secondary diabetes mellitus with ketoacidosis, [not stated as uncontrolled, or unspecified/uncontrolled]

249.20 — 249.21

Secondary diabetes mellitus with hyperosmolarity, [not stated as uncontrolled, or unspecified/uncontrolled]

249.30 — 249.31

Secondary diabetes mellitus with other coma, [not stated as uncontrolled, or unspecified/uncontrolled]

249.40 — 249.41

Secondary diabetes mellitus with renal manifestations, [not stated as uncontrolled, or unspecified/uncontrolled]

249.50 — 249.51

Secondary diabetes mellitus with ophthalmic manifestations, [not stated as uncontrolled, or unspecified/uncontrolled]

249.60 — 249.61

Secondary diabetes mellitus with neurological manifestations, [not stated as uncontrolled, or unspecified/uncontrolled]

249.70 — 249.71

Secondary diabetes mellitus with peripheral circulatory manifestations, [not stated as uncontrolled, or unspecified/uncontrolled]

249.80 — 249.81

Secondary diabetes mellitus with other specified manifestations, [not stated as uncontrolled, or unspecified/uncontrolled]

249.90 — 249.91

Secondary diabetes mellitus with unspecified complication, [not stated as uncontrolled, or unspecified/uncontrolled]

At first glance, it’s obvious the secondary diabetes subcategories (at the fourth digit) mirror those in the primary diabetes category 250. For instance, 249.1 and 250.1 both represent diabetes with ketoacidosis, the differing factor being whether the condition is primary or secondary. The fifth digit for the new codes represents whether the condition is documented as uncontrolled or not, just as the fifth digits in category 250 do. Since the codes are so similar, how are coding professionals to differentiate between them?

What You Need to Know

First, it’s important to understand the primary presentations of the diabetic condition. Type 1 primary diabetes is generally considered to be due to genetic factors, whereby the pancreas does not produce insulin in sufficient quantities to regulate blood glucose levels. Type 2 primary diabetes results in insulin resistance; although the body produces insulin, the body’s cells don’t respond appropriately to the insulin. Type 2 primary diabetes may be managed by engaging in exercise and modifying the diet, although some Type 2 diabetic patients require insulin in either an oral or injectable form. There is a genetic component to Type 2 diabetes, but since in many cases it can be managed through exercise and diet, its etiology is also considered to be environmental.

The major differentiating factor of secondary diabetes is the presence of another underlying condition that is determined to be the cause of the diabetes. While the ability to track these patients is necessary, it’s also important to understand that secondary diabetes is a very uncommon condition, relatively speaking. The National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK) estimates its incidence at 1 percent to 2 percent of total diabetes cases and the National Diabetes Education Program puts the figure at 1 percent to 5 percent of total diabetic cases. Some of the underlying causes that can cause secondary diabetes include:

  • chronic pancreatitis, hemochromatosis (excessive absorption of iron), pancreatic cancers, trauma to the pancreas, pancreatic damage due to malnutrition and other endocrine diseases that affect pancreas function or damage the insulin-producing beta cells;
  • endocrine disorders, including Cushing’s syndrome (involving overactive adrenal glands), hyperthyroidism and conditions involving excessive levels of growth hormones such as acromegaly;
  • liver diseases, including hepatitis C and fatty liver disease;
  • some carcinoid tumors of the lungs, intestines or stomach, along with adrenal and pituitary tumors that can cause secondary diabetes as a result of production of a hormone that causes the adrenal glands to overproduce cortisol;
  • celiac disease and other autoimmune diseases;
  • drugs and chemical agents, including:
    • antihypertensive diuretics and beta blockers;
    • hormone supplements including estrogen, birth control pills, injected contraceptives, growth hormones, anabolic steroids and hormones prescribed for prostate cancer;
    • antipsychotics, lithium and some antidepressants;
    • antiretrovirals (HIV drugs);
    • some anticonvulsants;
    • some chemotherapy drugs; and
    • immunosuppressives, including corticosteroids.
  • Surgical treatments, including:
    • Pancreatectomy: total pancreatectomy, primarily performed for pancreatic cancer or severe pancreatic disease, causes diabetes; partial pancreatectomy sometimes does, depending on how many of the beta cells are excised;
    • Orchiectomy, which may be performed for testicular cancer or, like hormonal drug therapy, a form of androgen deprivation therapy for prostate cancer, which may increase a man’s risk of secondary diabetes.

Diagnosis & Treatment

Secondary diabetes is diagnosed in much the same way as primary diabetes. Patients with conditions known to cause secondary diabetes are monitored on a regular basis with serum glucose testing before any symptoms appear. The physician may also order blood tests for pancreatic enzymes to rule out pancreatitis, thyroid tests to identify hyperthyroidism or C peptide tests to assess levels of insulin in the blood. The coder should be aware of these diagnostic studies and ensure the documentation in the medical record reflects the findings from such tests.

Treatment for secondary diabetes most often involves treatment of the underlying condition. In some cases, the diabetes is reversible if the underlying condition is found and treated expeditiously. Many cases of secondary diabetes are treated like Type 2 cases, since their presentation is similar to the insulin resistance found in Type 2 patients. In other cases that may involve destruction of the insulin-making beta cells (such as those in total pancreatectomy patients), the treatment may resemble that for many Type 1 patients, and insulin injections may be required. Coding staff should be reminded that the type of treatment provided should not be the major factor in classifying the disease, but it may represent a clue that can assist the decision-making process.

Because the findings and treatment of secondary diabetes may be similar to that involving Type 1 or Type 2 primary diabetes, it’s essential medical staff be made aware that documentation of secondary diabetes should be clearly indicated in the medical record. Endocrinologists should be informed that the codes for secondary diabetes are available and that accurate tracking of these patients over time will help in prevention and treatment strategies.

ICD-10 & Diabetes Coding

ICD-10-CM provides much more specificity in diabetes coding. In addition to category E10 for Type 1 and E11 for Type 2 diabetes, code category E08 represents diabetes mellitus due to an underlying condition, and category E09 represents drug or chemical-induced diabetes mellitus. The underlying condition in E08 includes such disorders as cystic fibrosis, pancreatitis and other underlying diseases that have the ability to cause diabetes. Within these categories, corresponding subcategories and codes represent very specific manifestations of diabetes, including:

  • hyperosmolarity and ketoacidosis;
  • didney, ophthalmic, neurological or circulatory system complications;
  • diabetic arthropathy;
  • skin complications;
  • oral complications; and
  • hypoglycemia.

In addition, combinations of underlying condition and manifestation are presented. For example, the following code represents three separate clinical concepts:

E08.321 Diabetes mellitus due to underlying condition with mild nonproliferative diabetic retinopathy with macular edema

Coders must be able to differentiate between the various types of diabetes, determine which conditions are manifestations of the disease and follow the many instructional notes in order to assign all required codes appropriately.

Take the quiz on page 2 to test your knowledge on secondary diabetes.

1. Most experts agree that the etiology of secondary diabetes is which of the following underlying causes?
a. genetic disorders
b. genetic and environmental disorders
c. drug induced causes only
d. factors other than genetic or environmental disorders

2. Secondary diabetes is primarily treated with which therapies?
a. Similar treatments to those provided to a primary diabetes Type 1 patient.
b. Treatment aimed at the underlying cause, depending on whether or not the patient’s body is producing insulin.
c. Similar treatment to a primary diabetes Type 2 patient, depending on presentation and whether the patient’s body is producing insulin.
d. Completely different treatment than that for primary diabetes.

3. The cells in the body that are responsible for producing insulin are:
a. beta cells
b. Islets of Langerhans
c. alpha cells
d. delta cells

4. Secondary diabetes can cause which of the following conditions?
a. Ketoacidosis
b. Diabetic nephropathy
c. Diabetic neuropathy
d. All of the above

This month’s column has been prepared by Cheryl D’Amato, RHIT, CCS, director of HIM, and Melinda Stegman, MBA, CCS, clinical technical editor, OptumInsight (, which specializes in the development and use of software and e-commerce solutions for managing coding, reimbursement, compliance and denial management in the health care marketplace.

Coding Clinic is published quarterly by the American Hospital Association.
CPT is a registered trademark of the American Medical Association.


1. d. Most experts agree that secondary diabetes is caused by factors other than genetic or environmental and may be due to other disease processes, past surgical history or drug therapy.

2. b. Since secondary diabetes is caused by an underlying condition or factor, most often treatment is directed at that condition, with diabetes treatment focused on whether the patient’s body is producing insulin or requires replacement.

3. a. While all of the cells listed in question 3 reside in the pancreas, it is the beta cells that are responsible for producing insulin, vital to the body’s glucose use.

4. d. Secondary diabetes may be manifested in the same ways as primary diabetes and may affect the same body systems, such as the kidney, neurological system, the eyes or may produce conditions such as ketoacidosis.

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