Hyperosmolarity and acidosis in diabetes mellitus: a three-year experience in Rhode Island.

OBJECTIVES: Diabetic acidosis (DA) and the diabetic hyperosmolar state (DHS) are generally considered to be two distinct clinical entities. However, clinical experience and the literature suggest that there may be some overlap. The purposes of this study were 1) to establish the proportion of overlap cases, 2) to identify any occurrence of DHS in diabetic patients under the age of 30 years (likely type I) and any occurrence of DA in diabetic patients over the age of 60 years (likely type II), 3) to describe clinical factors associated with the development of DA and DHS, and 4) to identify factors that influence the prognosis of DHS. PATIENTS AND METHODS: 613 cases were identified by retrospective chart review, using discharge information from all 15 Rhode Island community hospitals during 1986, 1987, and part of 1988. DA alone [serum glucose (glu) greater than 300 mg/dL, bicarbonate (HCO3) less than 15mEq/L, calculated total serum osmolarity (osm) less than or equal to 320 mOsm/L] was the diagnosis for 134 subjects (22%), DHS alone (glu greater than 600 mg/dL, HCO3 greater than or equal to 15mEq/L, osm greater than 320 mOsm/L), for 278 subjects (45%), and a mixed case (glu greater than 600 mg/dL, HCO3 less than 15 mEq/L, osm greater than 320 mOsm/L), for 200 subjects (33%). Information about serum or urinary ketones was available for 109 subjects who had DA alone [103 had diabetic ketoacidosis (DKA)] and 144 subjects who had mixed DA and DHS (131 had mixed DKA and DHS). All the data were also analyzed using the effective osmolarity and a cutoff of 310 mOsm/L for this alternative case definition.
RESULTS: Patients with DA alone were younger (mean age 33 years) and patients with DHS alone were older (mean age 63 years). However, 28 (10%) of the 278 cases of DHS alone and 72 (36%) of the 200 cases of mixed DA and DHS occurred in patients under the age of 30. Eighteen cases (13%) of DA alone and 62 cases (31%) of mixed DA and DHS occurred in patients over the age of 60. The results were not substantially changed when effective osmolarity greater than 310 mOsm/L was used to define hyperosmolarity and when only cases with documented DKA were included. An infection was the most common precipitating factor of DA (30%), DHS (27%), and mixed cases (32%). Other common associated factors included noncompliance with treatment (20% for DA, 12% for DHS, and 22% for mixed cases) and previously undiagnosed diabetes (24% for DA, 18% for DHS, and 10% for mixed cases). Nursing home residents accounted for 0.7% of DA cases, 18% of DHS cases, and 4.5% of mixed cases. Mortality was 4% for DA, 12% for DHS, and 9% for mixed cases. The mortality for DHS is the lowest reported in the literature, continuing a downward trend that began in the 1970s. Nonsurvival was associated with older age, higher osmolarity, and nursing home residence. Survival was associated with the presence of an infection.
CONCLUSIONS: 1) many patients experience mixed DA (DKA) and DHS rather than either condition alone, 2) both DA (DKA) and DHS occur in young and old diabetic persons, 3) infection is the most common predisposing factor for either condition, and 4) higher osmolarity, older age, and nursing home residence are associated with nonsurvival in DHS.