The study utilised a cross sectional design and was carried out at Hindu Mission Hospital, West Tambaram, Chennai. In-patients admitted in a hospital with diabetes and between the age of 18-75 of either gender were included in the study. The average duration of admission was three days. The study was approved by institutional ethics committee of the hospital in December 2017 (HMH/IEC/2017/EA32). All study procedures were carried out in accordance with guidelines as laid out in the Declaration of Helsinki. All the patients included had provided written informed consent and were explained about the study and its nature.

The biochemical parameters such as blood glucose levels (fasting, postprandial and random) were estimated by GOD-POD method [10], HbA1C- was assessed using nephelometry method [11], all electrolytes such as sodium, potassium, chloride and bicarbonate were assessed using direct and indirect Ion Selective Electrodes (ISEs) method [12]. Urea was measured by UV Kinetic method [13] and Creatinine by Jaffe Method [14]. Patients with HbA1C level above 7% were considered as uncontrolled diabetics. Hyponatremia was defined as sodium concentration less than 135 mmol/L, with severe hyponatremia less than 120 mEq/L. Hypochloremia was defined as chloride ion lower than 97 mEq/L while hyperchloremia was defined as a chloride level higher than 107 mEq/L. Hyperkalemia was defined as potassium level greater than 5 mEq/L. Hypokalemia was diagnosed when serum potassium level was lesser than 3.5 mEq/L. Elderly was defined as patients above 65 years of age.

Data were represented as mean±SD or median with inter-quartile range or frequency with percentage. Normality of data was assessed using Q-Q plot. Independent t-test or Mann-Whitney test was used to assess if there was significant difference in means or median. Chi-square test was used to see if there was a significant difference in the frequency of electrolyte disturbances between the groups. A p-value of less than 0.05 was considered statistically significant. The calculations were performed using a statistical program (SPSS V.16.0, Chicago, IL).

A total of 342 subjects were included in the study, of which 195 (57%) had uncontrolled DM. Patients with uncontrolled DM had a significantly longer duration of the illness (p=0.02). There were no major differences in the baseline characteristics between uncontrolled and controlled diabetic subjects [Table/Fig-1]. The frequency of hyponatremia, hypokalemia, hyperkalemia, hypochloremia and hyperchloremia was 33%, 16%, 6%, 31% and 2.7% respectively.

In patients with diabetes, Hyponatremia was more common in patients with uncontrolled sugars than those with well controlled blood sugars. (38.46 vs 27.73%, p=0.01) Hypochloremia was more common among subjects with uncontrolled DM (23.6 vs 17.55%, p=0.01) [Table/Fig-2]. A 22% of the present study population had hypochloremic metabolic alkalosis.

The proportion of patients with hypokalemia or hyperkalemia did not differ between the two groups. Hypokalemia was more common among users of loop diuretics. Hyponatremia was not seen at a greater frequency among loop diuretic users. Patients on insulin therapy were more likely to have hyponatremia than non-insulin users. (p=0.01) [Table/Fig-3]. Present study showed that the severity of hyponatremia did not differ significantly between patients with controlled and uncontrolled blood sugars [Table/Fig-4]. There was no difference in the severity of hyponatremia between elderly and non-elderly subjects [Table/Fig-5].

Although, it is well known from literature that electrolyte disturbances can possibly occur in diabetic patients, there are limited studies that have documented the magnitude of electrolyte disturbances in South Indian population. There are substantial differences in the dietary habits, lifestyle and genetics among patients in the Indian sub-continent. Hence, it is worthwhile to perform a region based study.

In this study, the most common electrolyte abnormality seen was hyponatremia, with almost one third of the subjects reporting with sodium under 130 mEq/L. There is a significant variability in the incidence of hyponatremia among hospitalised subjects ranging from 5 to 35% [15]. In this study, 9% of subjects reported severe hyponatremia while 25% reported moderate hyponatremia. As expected, patients with uncontrolled blood sugar were at a greater risk to develop hyponatremia, due to the inability of kidney to maintain control of homeostatic mechanisms involving stimulation of thirst, secretion of Antidiuretic Hormone (ADH), and renal handling of filtered sodium.

The frequency of hyponatremia was higher in elderly as compared to non-elderly participants. However severe hyponatremia was not found to be higher among elderly subjects, which could be because of the lack of significant difference in usage of diuretics between these populations. Some of the drugs which have been shown to be associated with high risk of hyponatremia besides diuretics include selective serotonin reuptake inhibitors, angiotensin-converting-enzyme inhibitors, opioids and anti-arrhythmics [16]. Present study participants did not have any known chronic usage of these drugs. However drug induced hyponatremia is more prevalent as a chronic presentation and as we measured the sodium levels on admission, the possibility of some of these subjects to have chronic hyponatremia cannot be ruled out. Present study did not show a mortality difference between patients with hyponatremia and normonatremia. Previous studies have documented that hyponatremia is a risk factor for increased mortality in the hospitalised patients [17,18]. It is possible that the correction of sodium levels during hospitalisation could have reversed the potential risk caused by hyponatremia as a risk factor for mortality in diabetic subjects.

Present study also showed that the frequency of hypokalemia was 16% and that of hyperkalemia was 6% in the study population. There was no significant difference in the frequency of these electrolyte disturbances between controlled and uncontrolled diabetic subjects. In a large Swedish health care system, where data was obtained from 364,955 patients, the incidence of hypokalemia was found to be 13% and that of hyperkalemia in 7% of the population [19]. The study had also reported that the odds of developing hyperkalemia were 1.62 in diabetic subjects compared to non-diabetic subjects. Previous studies have reported that some of the strong risk factors for hypokalemia include diuretic usage, losses from the gastrointestinal tract including diarrheal episodes and the use of laxatives and diabetic ketoacidosis [20]. However, in the present study population, we did not observe significant increase in the risk of hypokalemia with insulin usage. The usage of potassium sparing diuretics did not have an effect on the incidence of hypokalemia in our population. It is not known if these results were so because of the reduced duration of intake of these drugs in this study population, a variable which was not measured in the study.

Present study also revealed that 31% of the subjects had hypochloremia and 2% of them presented with hyperchloremia during admission. These findings are in agreement with a study done among critically ill patients with septic shock where the frequency of hypochloremia was found to be 35% [21]. However, a study done among 488 Japanese patients with critical illness showed a much lesser percentage of 8% [22]. In a retrospective study that assessed hospital admissions, those subjects with a serum chloride above 108 and below 100 mmol/L were at a greater predilection for succumbing to in-hospital mortality [23]. Nevertheless, this study did not show any association between the occurrence of hypochloremia and mortality. It is possible that the correction of chloride during hospital stay could have reduced the mortality risk. One of the most common causes for hypochloremia is excess use of diuretics, but this study did not show a greater preponderance of hypochloremia among diuretic users. It is possible that the increased frequency of hypochloremia seen among this study population could be due to other factors such as excess vomiting or nasogastric suctioning [24]. Nearly 22% of this study population had hyperchloremic metabolic alkalosis as defined by a chloride: sodium ratio <0.75 and sodium-chloride difference >37 mmol/L and of these 17.5% had hypokalemia. Thus, it is pertinent to study the electrolyte disturbances among diabetic subjects admitted in the hospital as they are at a greater risk of developing complications due to the same.

The present study did not look for the changes in the electrolyte concentration during the hospital stay and thus those patients who developed electrolyte disturbances after few days of hospital stay were not identified. Authors did not measure the urine concentration of electrolytes and having these variables would help us to characterise patients better.

Diabetic patients have a greater predilection to develop electrolyte disturbances. The most common electrolyte disturbances seen were hyponatremia and hypochloremia.