Diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS) are serious metabolic emergencies that affect patients with type 1 and type 2 diabetes. DKA and HHS are responsible for about 100,000 hospital admissions per year,¹ and account for one of every four dollars spent on adult patients with diabetes.² In one study³ that included 172,796 admissions from 1981 to 1989 in a county teaching hospital, DKA accounted for 28.7 percent of all patients admitted with a primary diagnosis of diabetes. The mortality rate for DKA is less than 5 percent, while the rate for HHS is about 15 percent.⁴ Important negative prognostic factors in both conditions include patients older than 65 years, hypotension, and coma. Basic common pathophysiologic mechanisms in both conditions consist of a reduction in circulating insulin with increased counterregulatory hormones (glucagon, catecholamines, cortisol, and growth hormone).⁴

Hyperglycemia occurs as a result of accelerated gluconeogenesis, glycogenolysis, and impaired glucose use by muscle and fat tissues. High levels of cortisol also stimulate the breakdown of proteins into amino acids, which then serve as precursors for gluconeogenesis. In patients with DKA, the lack of insulin combined with increased catecholamines results in accelerated lipolysis and production of excess free fatty acids leading to increased beta-oxidation and ketogenesis. However, in patients with HHS, residual beta-cell function, as measured by C-peptide, is adequate to prevent lipolysis, but cannot prevent hyperglycemia.

Although DKA was thought to occur only in patients with type 1 diabetes who require lifelong insulin, recent studies have identified some African Americans with type 2 diabetes who present with DKA, which initially required insulin, but subsequently may be treated with oral agents or diet.⁵ This condition has been given different names, including atypical diabetes, type 1.5 diabetes, or ketosis-prone diabetes.⁶

The review articles written by Trachten-barg⁷ and Stoner⁸ in this issue of American Family Physician reflect our current understanding of DKA and HHS, based on the recently updated American Diabetes Association guidelines⁹ that emphasize the importance of adequate fluid and electrolyte replacement, along with physiologic doses of insulin. Because HHS more frequently affects patients with type 2 diabetes and those who were previously undiagnosed, its presentation can be insidious. Older patients and nursing home residents may not be aware of their need for fluid, and consequently develop extensive dehydration and more severe hyperglycemia than patients with DKA.^4,10 Therefore, important preventive measures for HHS include frequent monitoring of hydration status, blood glucose levels, and other comorbid conditions.^4,9

The most frequent precipitating factor for DKA is infection.^4,9 However, recent studies^4,11 conducted at inner city hospitals in the United States suggest that the precipitating event often is omission of insulin because patients cannot access or afford medical care. Approximately 50 percent of admissions for DKA may be preventable with improvements in the care of these patients. Furthermore, it also has been shown that quarterly visits for children with type 1 diabetes to endocrine clinics can significantly reduce the number of emergency admissions for DKA.¹² A prospective study of 1,243 patients with type 1 diabetes from infancy to 19 years of age showed that elevated A1C levels, underinsurance, and concurrent presence of psychiatric disorders are important predictors of DKA.¹³

Home blood glucose monitoring equipment with the capability to measure beta-hydroxybutyrate on finger stick blood is now available.¹⁴ Home glucose monitoring may reduce admissions for DKA by causing patients to seek care earlier in the course of a hyperglycemic crisis. Because repeated admissions into the emergency department for DKA drain health care dollars, resources should be directed toward improving access to care and educational programs, particularly for socioeconomically disadvantaged groups. Furthermore, resources should be used to educate health care personnel and family members.

The use of low-dose intravenous insulin in the treatment of DKA and HHS is recognized as standard procedure.⁹ However, most recent studies^15,16 on fast-acting insulins (i.e., lispro and aspart) demonstrate that subcutaneous injections of these analogs every one to two hours in patients with mild or moderate DKA on the general hospital wards is as effective as the use of regular intravenous insulin in the intensive care unit, and results in 40 percent cost savings. Furthermore, long-acting peakless insulins such as glargine may provide adequate baseline insulin to reduce the incidence of chronic or acute hyperglycemia. The possibility of preventing DKA in this manner deserves further investigation in randomized clinical trials.