Topic: Diabetes Mellitus

Definition: Diabetes Mellitus (DM) is the body’s inability to process and regulate blood sugar. It is a chronic metabolic disease characterized by elevated levels of blood glucose, which leads over time to serious damage to blood vessels, eyes, kidneys, and nerves. 

• Prediabetes is recognized in individuals who are at high risk of developing diabetes. It is identified in those with an A1C of 5.7-6.4%, an impaired fasting glucose (IFG) of 100-125mg/dL, or an impaired glucose tolerance (IGT) of 140-199mg/dL in a two-hour plasma glucose value.  
• Type 1 diabetes (“Juvenile”) is characterized by absolute insulin deficiency due to autoimmune destruction of pancreatic beta cells. It is typically diagnosed in children and young adults and requires lifelong insulin therapy. 
• Type 1.5 diabetes is associated with autoimmune disease and is referred to as latent autoimmune diabetes in adults (LADA). This is caused by beta cell failure where insulin-producing cells are destroyed. Individuals may not require insulin in early stages, and this commonly occurs between the ages of 30-50 years of age.  
• Type 2 diabetes (“Adult”) is primarily due to peripheral resistance to insulin. The pancreas may initially produce insulin, but cells become resistant. It is often associated with obesity and a sedentary lifestyle and managed through lifestyle changes, medication, and sometimes insulin therapy. 
• Secondary diabetes is caused by an underlying disease (e.g., chronic pancreatitis, cystic fibrosis), certain medications (e.g., prednisone), and toxins (e.g., dioxin used in pesticides). 
• Pregnancy-induced diabetes (“Gestational”) develops during pregnancy and usually resolves after childbirth.  

Diagnostic Criteria:

Diagnosis of diabetes is based on: 

• HbA1c ≥ 6.5%, or  
• Fasting Blood Sugar (FBS) > 125 mg/dl, or 
• 2-hour Oral Glucose Tolerance Test (OGTT) > 200 mg/dl, or 
• Random glucose level > 200 mg/dl + Symptoms of hyperglycemia: polyuria, polydipsia, blurred vision

DM hyperglycemia: Blood sugar > 140 mg/dl 

DM hypoglycemia: Blood sugar < 70 mg/dl 

Diabetic Hyperosmolar Hyperglycemic State (HHS): Characterized by severe hyperglycemia, hyperosmolarity and dehydration without significant ketoacidosis, and usually some alteration in consciousness (coma if severe). HHS almost never occurs in Type 1 DM.  

Diagnostic Criteria include ALL of the following:

• Hyperglycemia: Blood sugar >= 600 mg/dL 
• Hyperosmolality: Serum osmolality > 320 mmol/L 
• Absence of significant ketonemia: B-hydroxybutyrate < 3.0 mmol/L or urinary ketones <2+ 

Absence of acidosis: pH >= 7.30 AND bicarbonate >= 15mmol/L (CO2/HCO3 on BMP or ABG) 

Diabetic Ketoacidosis (DKA): Characterized by hyperglycemia, acidosis, elevated ketones, and dehydration. Occurs primarily in Type 1 DM patients but can occur in Type 2. Diagnostic criteria require ALL the following:  

• Hyperglycemia: Blood sugar >= 200 mg/dL or history of DM 
• Ketosis: B-hydroxybutyrate >= 3.0 mmol/L or urinary ketones >= 2+ 
• Acidosis: pH < 7.30 and/or bicarbonate < 18 mEq/L (CO2/HCO3 on BMP or ABG) 

Ketones are produced in the presence of severe insulin deficiency. The predominant ketones being acetoacetate, acetone, and beta-hydroxybutyrate (BHB). The usual test for serum ketones measures all three of these ketones to some extent. The BHB test can be specifically ordered as a separate test and is believed to be an accurate measure of severity and progression of DKA. In normal circumstances, BHB is undetectable (< 0.6 mmol/L), 1.0 mmol/L requires attention, and > 3.0 mmol/L (as in most DKA cases) is severe.  

Euglycemic diabetic ketoacidosis (DKA) is a rare acute life-threatening metabolic emergency characterized by ketoacidosis and lower blood glucose (< 250 mg/dL) that can occur in patients with type 1 or type 2 diabetes mellitus. Potential causes are certain diabetic medications (e.g., Jardiance®, Farxiga®, Invokana®), pregnancy, fasting, bariatric surgery, gastroparesis, insulin pump failure, cocaine intoxication, chronic liver disease, and glycogen storage disease.

The pathophysiology of euglycemic DKA involves poor oral carbohydrate intake, milder degree of insulin deficiency or resistance and increased glucagon/insulin ratio.

Diagnostic Criteria:

• Relatively lower blood glucose (< 250 mg/dL) 
• pH <7.30, and 
• Bicarbonate <18, and 
• Elevated serum ketones (e.g., beta-hydroxybutyrate >3.0) 
• With exclusion of other causes of high anion gap metabolic acidosis. 

Diabetic gastroparesis is a common manifestation of diabetes. Characteristics typically include vomiting without diarrhea, dilated stomach/abdominal pressure, is frequently spontaneous without precipitating event, tends to be recurrent and caused by autonomic neuropathy. Often overlooked or confused with gastritis, peptic disease, and other GI disorders. Reglan® (metoclopramide) is the best treatment and very specific for gastroparesis.  

Hyponatremia with diabetic hyperglycemia: In diabetic hyperglycemia, glucose dilutes sodium which makes the measured sodium level lower than it really is. Therefore, it is necessary to calculate a corrected sodium to get the true sodium value to determine if a patient has hyponatremia or hypernatremia (or a normal sodium level).  

• To calculate the corrected sodium level in patients with hyperglycemia use: Measured Sodium + 0.016 x (Glucose – 100). 
• Example 1: Glucose 700 with measured sodium 128 that falsely appears to be hyponatremia. The corrected sodium level = 137.6, which is normal and would be considered “pseudohyponatremia.” (Calculation: 128 + 0.016 x 600 = 137.6)  
• Example 2: Glucose 700 with measured sodium 142 (normal). The corrected sodium level is 151.6 (hypernatremia). (Calculation: 142 + 0.016 x 600 = 151.6)  

TREATMENT

• Treatment of HHS and DKA is complicated and overlaps but includes insulin (usually starting with IV), IV fluids, correction of electrolyte imbalance, monitoring of response, and many other things depending on the clinical circumstances. Management of complications depends on the specific complication and its manifestations.
• Treatment of euglycemic DKA is on the same principles as for DKA with correction of dehydration, electrolytes deficit and insulin replacement, although IV fluids containing dextrose (e.g., D5NS) may be needed to prevent hypoglycemia. 

Coding Considerations:

• CMS-HCCs 36-38 (V28.0) for diabetes are all weighted the same whether the patient has any complications or not.
• Diabetic complications listed in the ICD-10 Index and Tabular (except those indexed as “NEC”) are automatically linked (“with“) and the diabetes code can be assigned unless the provider specifically stated as unrelated (OCG I.A.15). In most cases, a combination code identifies the type of diabetes and the complication. For “other specified” diabetic complication (E11.69), an additional code is also assigned for the complication. Assign as many codes from categories E08 – E13 as needed to identify all the associated conditions that the patient has.
• Coding Clinic: The “with” guideline does not apply to diabetes codes with index entries that include “not elsewhere classified (NEC)”, e.g., arthropathy NEC, circulatory complication NEC, oral complication NEC. If a condition is not listed as “with” diabetes or it is listed as an “NEC” code in the index, the physician must establish a causal relationship to assign the combination code.
• To illustrate, a diabetic patient with a “skin ulcer” is not assigned a code for diabetic skin ulcer. The skin ulcer would have to be associated with diabetes by the provider. However, a foot ulcer is automatically linked to diabetes without provider clarification. 
• The term “Type 1.5” has been used clinically to describe type 1 patients with insufficient insulin production who also have an element of peripheral insulin resistance characteristic of type 2. In this case, assign a code from category E13, other specified diabetes (Coding Clinic Third Quarter 2018, p.4).
• Code assignment for euglycemic DKA is the same as DKA, codes E10.10 or E11.10 depending on whether the patient has Type 1 or Type 2 DM. There are no codes to specify “euglycemic.” 
• Do not assign a code for “hyponatremia” in hyperglycemic patients with pseudohyponatremia. The low sodium would be considered an abnormal lab finding that is always inherent to hyperglycemia. Be sure to calculate a corrected sodium (see above) to get the true sodium value to determine if a patient truly has hyponatremia or hypernatremia (or a normal sodium level). 
• Do not assign the ketoacidosis code for documentation of diabetic “ketosis.” Even though this term is indexed to ketoacidosis, it is not a clinically valid diagnosis unless acidosis is present. 
• Terms that qualify for assignment to diabetes with hyperglycemia (E11.65) include out of control, inadequate control, or poorly controlled. “Uncontrolled” must be clarified/queried as hyper- or hypoglycemia.
• New code for FY2026: E11.A Type 2 diabetes mellitus without complications in remission. This code should be used when a patient with type 2 diabetes no longer requires medication to control their blood sugar levels, and their diabetes is considered to be “in remission”. Please note: the term “resolved” is not synonymous with remission.” 

CDI Practice Considerations:

• Acute diabetic complications, i.e., HHS, DKA, diabetic coma, have MCC status and DM with gangrene is a CC. All other diabetic complications are non-CCs. 
• For APR-DRGs nearly all Type 1 DM complications are standard SOI-2, and some of the less common chronic complications are SOI-2. 
• Diabetic complications, when coded, are essential for reporting DRG assignments, Severity of Illness and HCCs:

  Common chronic diabetic complications include: 

• • Circulatory: Peripheral vascular/arterial disease (PVD) usually lower extremities, diabetic microangiopathy 
  • Neuropathy: Mononeuropathy, polyneuropathy, autonomic neuropathy (e.g., gastroparesis) 
  • Nephropathy: Chronic kidney disease, glomeruloscleroses 
  • Ophthalmic: Retinopathy, macular edema; diabetic cataract; diabetic glaucoma is caused by retinopathy 
  • Skin: Non-pressure foot ulcer and ischemic and non-ischemic non-pressure ulcers typically of the lower extremities. Osteomyelitis is a common complication of diabetic foot ulcers 

Query Opportunity:

• Query as necessary, based on clinical indicators, to clarify diabetic complications if not already an assumed link. Example: 
• Querying the relationship between diabetes and cellulitis may be appropriate in certain circumstances, i.e., when as principal diagnosis the diagnosis impacts the MS-DRG or APR-DRG and it is clinically indicated. Clinical indicators of diabetic cellulitis include a diabetic patient with PVD, neuropathy, skin ulcer, usually of the lower extremity; history of minor skin injury (scratch, abrasion); or diabetes that are poorly controlled. Routinely querying for a relationship between a condition, such as cellulitis, and diabetes is unnecessary and should be discouraged. 

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