Clinical features, mortality, hospital admission, and length of stay of a cohort of adult patients with diabetic ketoacidosis attending the emergency room of a tertiary hospital in Spain

Comparison of clinical characteristics and treatment outcomes between initially diagnosed type 1 and type 2 diabetes mellitus patients presenting with diabetic ketoacidosis

OBJECTIVE

Patients with type 1 diabetes (T1DM) and type 2 diabetes (T2DM) can present with diabetic ketoacidosis (DKA) as the first manifestation. Differentiating types of newly diagnosed diabetes could provide appropriate long-term management. Therefore, we conducted this study to compare clinical characteristics and outcomes between initially diagnosed type 1 and type 2 diabetes mellitus patients presenting with DKA.

MATERIALS AND METHODS

A retrospective study was conducted on adult patients who presented with DKA as the first diagnosis of diabetes in our tertiary hospital between January 2005 and December 2019. Demographic data, precipitating causes, laboratory investigations, treatment, and outcomes were obtained by chart review. The primary outcome was to compare the clinical characteristics of initially diagnosed patients with T1DM and T2DM who presented with DKA.

RESULTS

A total of 100 initially diagnosed diabetic patients who presented with DKA were analyzed (85 T2DM patients and 15 T1DM patients). Patients with T1DM were younger than patients with T2DM (mean age 33 ± 16.2 vs. 51 ± 14.5 years, p value < 0.001). Patients with T2DM had a higher body mass index, family history of diabetes, precipitating factors, plasma glucose, and lower renal function than those with T1DM. There was no difference in resolution time or DKA management between T1DM and T2DM patients. The overall mortality rate of DKA was 4%.

CONCLUSION

In this population, most adult patients who presented with DKA had T2DM. Older age, obesity, a family history of diabetes, and the presence of precipitating factors were strong predictors of T2DM. We can implement the same clinical management for DKA in both T1DM and T2DM patients. However, T2DM patients had longer hospitalization than T1DM patients. After DKA resolution for 12 months, more than half of patients with T2DM could discontinue insulin. Therefore, the accurate classification of the type of diabetes leads to appropriate treatment.

Combined hyperglycemic crises in adult patients already exist in Latin America

INTRODUCTION

Diabetes mellitus is one of the most common diseases worldwide, with a high morbidity and mortality rate. Its prevalence has been increasing, as well as its acute complications, such as hyperglycemic crises. Hyperglycemic crises can present with combined features of diabetic ketoacidosis and hyperosmolar state. However, their implications are not fully understood.

OBJECTIVE

To describe the characteristics, outcomes, and complications of the diabetic population with hyperglycemic crises and to value the combined state in the Latin American population.

MATERIALS AND METHODS

Retrospective observational study of all hyperglycemic crises treated in the intensive care unit of the Fundación Valle del Lili between January 1, 2015, and December 31, 2020. Descriptive analysis and prevalence ratio estimation for deaths were performed using the robust Poisson regression method.

RESULTS

There were 317 patients with confirmed hyperglycemic crises, 43 (13.56%) with diabetic ketoacidosis, 9 (2.83%) in hyperosmolar state, and 265 (83.59%) with combined diabetic ketoacidosis and hyperosmolar state. Infection was the most frequent triggering cause (52.52%). Fatalities due to ketoacidosis occurred in four patients (9.30%) and combined diabetic ketoacidosis/hyperosmolar state in 22 patients (8.30%); no patient had a hyperosmolar state. Mechanical ventilation was associated with death occurrence (adjusted PR = 1.15; 95 % CI 95 = 1.06 - 1.24).

CONCLUSIONS

The combined state was the most prevalent presentation of the hyperglycemic crisis, with a mortality rate similar to diabetic ketoacidosis. Invasive mechanical ventilation was associated with a higher occurrence of death.

Enhancing outcome prediction by applying the 2019 WHO DM classification to adults with hyperglycemic crises: A single-center cohort in Thailand

BACKGROUND AND AIMS

Hyperglycemic crisis is a metabolic catastrophe which can occur in any type of diabetes. In 2019, the World Health Organization (WHO) revised the classification of diabetes mellitus (DM) and established two new hybrid forms, latent autoimmune diabetes in adults (LADA) and ketosis-prone type 2 diabetes (T2D). This study aimed to determine clinical outcomes after a hyperglycemic crisis event in people with diabetes classified subtypes by 2019 WHO DM classification.

METHODS

A five-year (2015-2019) retrospective study of adult patients admitted with hyperglycemic crises was conducted. Types of diabetes were recategorized based on the 2019 WHO DM classification. Clinical characteristics, in-admission treatment and complications, long-term follow-up outcomes, and mortality were collected, analyzed, and compared.

RESULTS

A total of 185 admissions occurred in 136 patients. The mean age was 50.6 ± 18.4 years (49.3 % men). The annual average incidence of hyperglycemic crises was 5.2 events/1000 persons. The proportion of type 1 diabetes, T2D, LADA, ketosis-prone T2D, and pancreatic DM were 15.4 %, 69.1 %, 2.2 %, 11 %, and 2.2 %, respectively. In-hospital mortality was 3.7 % while cumulative mortality totaled 19.1 %. During the 24-month follow-up, ketosis-prone T2D had the highest success of insulin discontinuation (HR 6.59; 95 % CI 6.69-319.4; p < 0.001), while T2D demonstrated the highest mortality compared to others (HR, 2.89; 95%CI 1.15-6.27; p = 0.02).

CONCLUSION

The reclassification of diabetes based on 2019 WHO DM classification helped elucidate differences in long-term outcomes and mortality among DM types. The new classification, which separates ketosis-prone T2D from standard T2D, should be encouraged in clinical practice for precise and individualized management.

Incidence and determinants of diabetic ketoacidosis among people with diabetes in Woldiya comprehensive specialized hospital, Ethiopia: a retrospective cohort study

INTRODUCTION

Diabetic ketoacidosis is an acute complication of diabetes mellitus that is characterised by hyperglycemia, acidosis, and ketonuria. Diabetes is the most challenging public health problem in the twenty-first century for both developed and developing countries.

OBJECTIVE

To assess the incidence of Diabetic ketoacidosis and its determinants among adult people with diabetes at an Ethiopian Hospital.

METHOD

An institution-based retrospective cohort study was conducted among 390 adult people with diabetes attending services at Wolida Comprehensive Specialized Hospital. The consecutive sampling method was used to select study participant charts. Data were collected using a checklist prepared from different literature. The data were entered into EPI data version 4.6.0.5 and exported to STATA version 14.0 for further analysis. The Wiebull model was the best fitted model that was selected using the log-likelihood ratio method and the Akakian information criterion. Hazard ratios with their 95% confidence interval and p-value were computed.

RESULT

From the total 405 charts reviewed, 390 adult charts were included for analysis. A total of 121 DKA occurred from 5471 person-months of observation. The overall incidence rate of diabetic ketoacidosis was found to be 2.2 per 100 person-months (95% CI: 1.8- 2.6). Being urban dweller (AHR: 0.59, 95% CI: 0.36-0.99), having no family history of DM (AHR: 0.55, 95%CI: 0.31-0.97), presence of infection (AHR: 2.60, 95%CI = 1.06-6.39), having of any comorbidities (AHR: 4.31, 95% CI: 1.70-10.90), and having poor glycemic control (AHR: 7.45, 95% CI: 3.84-14.47) were significant determinants.

CONCLUSION AND RECOMMENDATIONS

The overall incidence of diabetic ketoacidosis in study area was relatively high. Poor glycemic control, the presence of infection, and comorbidity were determinants of diabetic ketoacidosis. There is a need to have close follow-up of people with diabetes who have comorbidity, infection, and poor glycemic control.

Clinical and biochemical determinants of length of stay, readmission and recurrence in patients admitted with diabetic ketoacidosis

BACKGROUND

The increasing prevalence of diabetic ketoacidosis (DKA) related admissions poses a significant burden on the healthcare systems globally. However, data regarding the predictors of healthcare resource utilization in DKA is limited and inconsistent. This study aimed to identify key predictors of hospital length of stay (LOS), readmission and recurrent DKA episodes.

METHODS

We undertook a retrospective cross-sectional analysis of all DKA admissions from 2015 to 2021 across four hospitals in Qatar. The primary outcomes were the length of stay (LOS), 90-day readmission and 6-month and 1-year DKA recurrence.

RESULTS

We included 922 patients with a median age of 35 years (25-45). 62% were males with type-1 diabetes-mellitus (T1DM) and type-2 DM (T2DM), present in 52% and 48% of patients. The median LOS was 2.6 days (IQR 1.1-4.8), and the median DKA resolution time was 18 h (10.5-29). Male-gender, new-onset DM, higher Charlson Comorbidity Index (CCI), lower haemoglobin, sodium and potassium, higher urea, longer DKA duration and MICU admission predicted a longer LOS in a multivariate regression analysis. None of the factors were significantly associated with 90-day readmission. Patients with pre-existing T1DM were more likely to have a six-month DKA recurrence than pre-existing T2DM. Patients with a 6-month DKA recurrence, female gender and T1DM had higher odds of 12-month recurrence, whereas a consult with a diabetes educator at the index admission was associated with decreased odds of recurrence.

CONCLUSIONS/INTERPRETATION

This is the most extensive study from the Middle-East region reporting on LOS, readmissions and the recurrence of DKA. Results from this study with a diverse population may be valuable for physicians and healthcare systems to decrease the diabetes-related healthcare burden in DKA patients.

Study of assessment of knowledge and understanding for coping with sick days among patients with diabetes in community pharmacy: a cluster randomized controlled trial (SAKURA trial)

BACKGROUND

Awareness regarding coping with sick days among patients with diabetes is limited. Thus, we evaluated the effectiveness of sick-day education by community pharmacists among patients with type 2 diabetes (T2D) using sick-day educational materials (sick-day cards).

METHODS

A cluster randomized controlled trial was conducted. Pharmacists in the intervention group educated patients with T2D on coping with sick days (adjusting medication dosage and seeking medical advice) using sick-day cards compared with the usual counseling. Differences in questionnaire scores ("Anxiety", "Intention", "Attitude", and "Knowledge" about sick days) before and after the intervention were compared between the groups.

RESULTS

Overall, 318 patients with T2D (intervention, 119; control, 199) participated in this study, and 270 (intervention, 92; control, 178) patients were examined. There were no significant differences in "Anxiety", "Intention", or "Attitude" scores between the two groups, but "Knowledge" scores improved in the intervention group. For all intervention groups (92/92), a physician reviewed and approved medication and adjustment doses for sick days on the cards.

CONCLUSIONS

According to patients' responses, sick-day education using teaching materials improved patient knowledge. This may help patients and their caregivers cope with sick days appropriately through medication dose adjustment and fluid intake. Research registration number: UMIN000043161 (February 1, 2021), https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr.cgifunction=brows&action=brows&recptno=R000048124&type=summary&language=J.

Clinical and biochemical predictors of intensive care unit admission among patients with diabetic ketoacidosis

BACKGROUND

Diabetic ketoacidosis (DKA) contributes to 94% of diabetes-related hospital admissions, and its incidence is rising. Due to the complexity of its management and the need for rigorous monitoring, many DKA patients are managed in the intensive care unit (ICU). However, studies comparing DKA patients managed in ICU to non-ICU settings show an increase in healthcare costs without significantly affecting patient outcomes. It is, therefore, essential to identify suitable candidates for ICU care in DKA patients.

AIM

To evaluate factors that predict the requirement for ICU care in DKA patients.

METHODS

This retrospective study included consecutive patients with index DKA episodes who presented to the emergency department of four general hospitals of Hamad Medical Corporation, Doha, Qatar, between January 2015 and March 2021. All adult patients (> 14 years) fulfilling the American Diabetes Association criteria for DKA diagnosis were included.

RESULTS

We included 922 patients with DKA in the final analysis, of which 229 (25%) were managed in the ICU. Compared to non-ICU patients, patients admitted to ICU were older [mean (SD) age of 40.4 ± 13.7 years vs 34.5 ± 14.6 years; P < 0.001], had a higher body mass index [median (IQR) of 24.6 (21.5-28.4) kg/m² vs 23.7 (20.3-27.9) kg/m²; P < 0.030], had T2DM (61.6%) and were predominantly males (69% vs 31%; P < 0.020). ICU patients had a higher white blood cell count [median (IQR) of 15.1 (10.2-21.2) × 10³/uL vs 11.2 (7.9-15.7) × 10³/uL, P < 0.001], urea [median (IQR) of 6.5 (4.6-10.3) mmol/L vs 5.6 (4.0-8.0) mmol/L; P < 0.001], creatinine [median (IQR) of 99 (75-144) mmol/L vs 82 (63-144) mmol/L; P < 0.001], C-reactive protein [median (IQR) of 27 (9-83) mg/L vs 14 (5-33) mg/L; P < 0.001] and anion gap [median (IQR) of 24.0 (19.2-29.0) mEq/L vs 22 (17-27) mEq/L; P < 0.001]; while a lower venous pH [mean (SD) of 7.10 ± 0.15 vs 7.20 ± 0.13; P < 0.001] and bicarbonate level [mean (SD) of 9.2 ± 4.1 mmol/L vs 11.6 ± 4.3 mmol/L; P < 0.001] at admission than those not requiring ICU management of DKA (P < 0.001). Patients in the ICU group had a longer LOS [median (IQR) of 4.2 (2.7-7.1) d vs 2.0 (1.0-3.9) d; P < 0.001] and DKA duration [median (IQR) of 24 (13-37) h vs 15 (19-24) h, P < 0.001] than those not requiring ICU admission. In the multivariate logistic regression analysis model, age, Asian ethnicity, concurrent coronavirus disease 2019 (COVID-19) infection, DKA severity, DKA trigger, and NSTEMI were the main predicting factors for ICU admission.

CONCLUSION

In the largest tertiary center in Qatar, 25% of all DKA patients required ICU admission. Older age, T2DM, newly onset DM, an infectious trigger of DKA, moderate-severe DKA, concurrent NSTEMI, and COVID-19 infection are some factors that predict ICU requirement in a DKA patient.

Diabetic Ketoacidosis Treatment Outcome and Associated Factors Among Adult Patients Admitted to the Emergency Department and Medical Wards at King Abdulaziz Medical City, Riyadh, Saudi Arabia

Background Diabetic ketoacidosis (DKA) is a life-threatening condition with high morbidity and mortality rates. It should be diagnosed immediately and managed intensively to prevent its significant complications. Objectives The aim of this study to assess DKA treatment outcome and associated factors among adult patients at King Abdulaziz Medical City Emergency Department and Medical Wards, Riyadh, Saudi Arabia. Materials and Methods A retrospective cross-sectional study was conducted using a chart review to assess DKA treatment outcome and associated factors. All patients who were admitted as DKA cases from September 2017 to August 2019 were selected by simple random sampling except those with incomplete charts or younger than 14 years. Data were entered and analyzed using SAS Version 9.4 (SAS Institute, Cary, NC, USA). Results A total of 223 reviewed charts were collected. The frequency of DKA recurrence in most of the patients was once per year (126 [56.5%]). The most common precipitating factor was inappropriate insulin therapy (104 [46.64%]). More than half of the patients (120 [53.81%]) got out of DKA management protocol within 24-72 hours with a hospital stay of less than or equal to five days. The mortality rate was 1.83%. Patients with two or more DKA episodes per year tended to be admitted to ICU more frequently than those with one episode (p=0.001). It was found that patients who had a duration of one to five years of diabetes mellitus were almost five times more likely to get out of DKA in more than 72 hours when compared with those who had a duration of more than five years (adjusted OR: 4.7; 95% CI: 1.34-16.60; p=0.01). Conclusions The findings of this study highlight that majority of DKA patients showed improvement and discharged with a very low mortality rate. Inappropriate insulin therapy was the most common precipitating factor; thus, educating diabetic patients about the complications of treatment non-compliance is an important part of management.

Structural, Dermal and Ungual Characteristics of the Foot in Patients with Type II Diabetes

Background and Objectives: Diabetes is a chronic and metabolic disease, considered as an important public health problem. The objective of this study was to determine the prevalence of podiatric pathology in type II diabetic patients. Materials and Methods: An observational descriptive study of prevalence in the endocrinology service of Complexo Hospitalario Universitario A Coruña (CHUAC) (A Coruña-Spain) was carried out (n = 153). Type II diabetic patients included, of legal age who signed the informed consent. Sociodemographic variables were studied (age, sex, body mass index (BMI), smoking habit, alcohol consumption, family history), disease variables (time of evolution of diabetes, treatments, low-density lipoprotein (LDL), high-density lipoprotein (HDL), glucose), podiatric variables: measurement of the footprint, metatarsal and digital formula, nail, skin, hindfoot and forefoot alterations. The data collection was done in 2018 and the data analysis was carried out in 2019. Results: The patients with type II diabetes had greater age, obesity and arterial hypertension it compared to the general population. Diabetic patients had a higher prevalence of flat feet than the general population (71.2% vs. 20.7%, p < 0.001), with a predominance of normal foot according to the podoscope. The predominant podological pathology was the presence of claw toes (94.8%), followed by dermal (78.4%) and nail (71.9%) alterations, and the Hallux Valgus (66.0%). The Clarke angle and the Chippaux index showed a Kappa concordance index of 0.26 with the type of footprint measured with the podoscope. The Staheli index showed a Kappa index of 0.27 associated with an observed agreement of 54%. Conclusions: This study shows that foot problems continue to be prevalent in subjects with type II diabetes mellitus and for this reason, podiatry is essential in its treatment.

Impact of Atrial Fibrillation on In-Hospital Outcomes in Patients With Diabetic Ketoacidosis

BACKGROUND

Diabetic ketoacidosis entails a huge health burden among patients with diabetes. Atrial fibrillation (AF) is the most common type of heart arrhythmia. This study aimed to evaluate the impact of AF on clinical outcomes in patients with diabetic ketoacidosis.

METHODS

Using the 2012-2014 National Inpatient Sample database, we identified adult patients hospitalized with diabetic ketoacidosis as the principal discharge diagnosis. The identified admissions were stratified into 2 cohorts based on the AF presence. We used multivariable regression models and propensity score matching models to evaluate in-hospital mortality, length of stay, comorbidities, and in-hospital complications.

RESULTS

The study included 478,890 adult patients who were admitted for diabetic ketoacidosis in the year 2012-2014. A total of 467,780 (97.68%) had no AF and 11,125 (2.32%) had AF. In both multivariable regression models and propensity score matching models, compared with nonatrial fibrillation group, the AF group had higher in-hospital mortality rates (2.36 [1.69-3.32], P < 0.001) and longer length of stay (5.5 versus 3.3 days, P < 0.001). AF was also associated with a significantly higher incidence of complications including septic shock, pulmonary failure, mechanical ventilation, neurological failure, cerebral edema, acute kidney injury, acute hematologic failure, and cardiac arrest.

CONCLUSIONS

Among patients who were hospitalized for diabetic ketoacidosis, comorbid AF led to increasing in-hospital mortality rates and longer length of stay. A potential explanation was that AF increased the risk of in-hospital complications including respiratory failure with a more frequent requirement for mechanical ventilation, cardiac arrest, and metabolic encephalopathy.

Correlation of acidosis-adjusted potassium level and cardiovascular outcomes in diabetic ketoacidosis: a systematic review

BACKGROUND

During the progress and resolution of a diabetic ketoacidosis (DKA) episode, potassium levels are significantly affected by the extent of acidosis. However, none of the current guidelines take into account acidosis during resuscitation of potassium level in DKA management, which may increase the risk of cardiovascular adverse events.

OBJECTIVE

To assess literature regarding the adjustment of potassium level using pH to calculate pH-adjusted corrected potassium level, and to observe the relationship of cardiovascular outcomes with reported potassium level and pH-adjusted corrected potassium in DKA.

METHODOLOGY

Seven databases were searched from inception to January 2018 for studies which had reported people with diabetes developing diabetic ketoacidosis, in relation to prevalence or incidence, fluid resuscitation or potassium supplementation treatment, treatment or cardiovascular outcomes, and experimentation with DKA management or insulin. Quality of studies was evaluated using Cochrane Risk of Bias and Newcastle Ottawa Scale.

RESULTS

Forty-seven studies were included in qualitative synthesis out of a total of 10,292 retrieved studies. Forty-one studies discussed the potassium level and blood pH at the time of admission, ten studies discussed cardiovascular outcomes, and only four studies concurrently discussed potassium level, pH, and cardiovascular outcomes. Only two studies were graded as good on the Newcastle Ottawa Scale. The reported potassium level was well within normal range (5.8 mmol/L), whereas pH rendered patients to be moderately acidotic (7.13). Surprisingly, none of the included studies mentioned pH-adjusted corrected potassium level and, hence, this was calculated later. Although mean corrected potassium was within the normal range (3.56 mmol/L), 13 studies had corrected potassium below 3.5 mmol/L and five had it below 3.0 mmol/L. Nevertheless, with the exception of one study, none discussed cardiovascular outcomes in the context of potassium or pH-adjusted potassium level.

CONCLUSION

The evidence surrounding cardiovascular outcomes during DKA episodes in light of a pH-adjusted corrected potassium level is scarce. A prospective observational, or preferably, an experimental study in this regard will ensure we can modify and enhance safety of existing DKA treatment protocols.

Predictors of acute gastrointestinal bleeding in diabetic ketoacidosis: a retrospective observational study in minority population

Background

Diabetic ketoacidosis (DKA) is a common acute complication of diabetes mellitus requiring aggressive medical management. We attempted to study the incidence and various clinical and laboratory variables associated with acute gastrointestinal bleeding (AGIB) and acute upper AGIB (AUGIB) in patients with DKA.

Methods

We conducted a retrospective chart review of all the patients admitted to our hospital with DKA between January 2010 and December 2015. We collected demographic, clinical, laboratory, endoscopy and hospitalization details using an electronic medical-record database. Patients were divided into two groups based on the occurrence of gastrointestinal bleeding.

Results

A total of 234 patients with DKA were admitted during this period, of which 27 (11.5%) patients had documented AGIB. The majority of patients had hematemesis (n=22, 9.4%) except two had rectal and three had occult bleeding. We did not notice any difference in age, gender and ethnicity distribution between the two groups. There was no difference in the serum levels of electrolytes, anion gap, pH and hemoglobin A1C between the two groups. However, patients with AGIB had significantly higher initial blood glucose levels (738 vs 613 mg/dL, p =0.014). There was also increased mortality (7.4% vs 4.8%) in patients with AGIB, but this did not reach statistical significance.

Conclusion

We conclude that higher initial serum blood glucose was associated with increased incidence of AGIB in patients admitted with DKA. We also noted increased in-patient mortality in patients with DKA who had AGIB, even though statistically insignificant. More aggressive measures to correct blood glucose levels may result in decreased incidence of AGIB, thereby reducing mortality during hospitalization in patients with DKA.

Diabetic emergencies - ketoacidosis, hyperglycaemic hyperosmolar state and hypoglycaemia

Diabetic ketoacidosis (DKA), hyperglycaemic hyperosmolar state (HHS) and hypoglycaemia are serious complications of diabetes mellitus that require prompt recognition, diagnosis and treatment. DKA and HHS are characterized by insulinopaenia and severe hyperglycaemia; clinically, these two conditions differ only by the degree of dehydration and the severity of metabolic acidosis. The overall mortality recorded among children and adults with DKA is <1%. Mortality among patients with HHS is ~10-fold higher than that associated with DKA. The prognosis and outcome of patients with DKA or HHS are determined by the severity of dehydration, the presence of comorbidities and age >60 years. The estimated annual cost of hospital treatment for patients experiencing hyperglycaemic crises in the USA exceeds US$2 billion. Hypoglycaemia is a frequent and serious adverse effect of antidiabetic therapy that is associated with both immediate and delayed adverse clinical outcomes, as well as increased economic costs. Inpatients who develop hypoglycaemia are likely to experience a long duration of hospital stay and increased mortality. This Review describes the clinical presentation, precipitating causes, diagnosis and acute management of these diabetic emergencies, including a discussion of practical strategies for their prevention.

Management of diabetic ketoacidosis and hyperglycemic hyperosmolar state in adults

Diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic syndrome (HHS) are two acute complications of diabetes associated with high mortality rate if not efficiently and effectively treated. Both entities are characterized by insulinopenia, hyperglycemia and dehydration. DKA and HHS are two serious complications of diabetes associated with significant mortality and a high healthcare costs. The overall DKA mortality in the US is less than 1%, but a rate higher than 5% is reported in the elderly and in patients with concomitant life-threatening illnesses. Mortality in patients with HHS is reported between 5% and 16%, which is about 10 times higher than the mortality in patients with DKA. Objectives of management include restoration circulatory volume and tissue perfusion, resolution of hyperglycemia, correction of electrolyte imbalance and increased ketogenesis.