This study was designed to investigate the measurements of serum levels of Na+ , K+ , Mg2+ and Ca2+ and their changes with serum glucose levels. Thirty treated diabetic patients (diet / OHA), aged between 23 to 27 years and having BMI of 17.9 to 22.54 kg/m2 were selected randomly from the outpatient department of BIRDEM.

1. Original Article
Comparative Study of Serum Electrolytes among
Treated Diabetic Subjects
Ruksana Karim1, Eram Mustafiz1, Tasmina Parveen2, SM Nurul Hassan3, Waheeda Nargis1, Matia Ahmed2
Abstract
This study was designed to investigate the measurements of serum levels of Na+
, K+
, Mg2+
and Ca2+
and their changes with serum glucose levels. Thirty treated diabetic patients (diet
/ OHA), aged between 23 to 27 years and having BMI of 17.9 to 22.54 kg/m2
were selected
randomly from the outpatient department of BIRDEM. The patients were grouped as Control
(Gr I, n=30) comprised of non-diabetic subjects with no family history of diabetes up to the
second generation; and Case (Gr II, n=30), comprised of treated diabetic patients. The Gr
II subjects were further divided into 3 groups from a to c on the basis of their fasting serum
glucose levels. Fasting serum glucose levels of these subgroups were as follows: 6-10
mmol/l for Gr IIa (n=10); 10-15 mmol/l for Gr IIb (n=10); and >15 mmol/l for Gr IIc (n=10).
Serum Na+
and Mg2+
levels were significantly low and serum K+
level was significantly high
in Gr IIc compared to Gr IIa but there was no significant difference between Gr IIa and Gr
IIb. However there was no significant difference of Ca2+
level between the control and
diabetic groups.
Key words: serum electrolytes, diabetes mellitus, fasting glucose
(J Uttara Adhunik Med Coll. 2013; 3(2) : 122-125).
1. Department of Biochemistry, Uttara Adhunik Medical College, Uttara, Dhaka
2. Department of Physiology, Uttara Adhunik Medical College, Uttara, Dhaka
3. Department of Anatomy, Uttara Adhunik Medical College, Uttara, Dhaka
Address for correspondence: Dr. Ruksana Karim, Professor & Head, Department of Biochemistry, Uttara Adhunik Medical
College, Uttara, Dhaka
Introduction
Ionized pools of sodium, potassium, magnesium and
calcium are among the most physiologically important
ions, the concentrations of which are critically
maintained in body fluids. Abnormal homeostasis of
these ions has been reported in diabetes mellitus both
as cause and consequence. Any disturbances of
these electrolytes disturb the whole metabolic process
leading to complications.
In a study carried out in France, interrelations between
glucose and electrolyte homeostasis were evaluated
in 193 IDDM out-patients1. Patients with blood glucose
values within 2.5 – 10 mmol/l had entirely normal levels
of serum Na+ and K+. In diabetic patients with different
levels of hyperglycemia, they showed gradual
hyponatremia and a rise in serum K+ level1.
According to reports in another study carried out in
68 IDDM Chinese patients, it was found that diabetes
mellitus was associated with disturbances in
electrolyte metabolism2. In the study it was shown
that there is a significant correlation of serum Na+ (r =
-0.323, p < 0.01), K+ (r = 0.416 P < 0.0001) and Mg2+
(r = -0.292, p < 0.02) with fasting glucose3. Thus in
patients with high fasting glucose, Na+ and Mg2+ tend
to be lower while K+ is higher3. Among the three
parameters, only serum Mg2+ significantly correlate
with the level of hemoglobin A1C and thus may be
related to long term control of diabetes. On the other
hand, the hyponatremia and hyperkalemia are more
likely to be related to short-term metabolic control as
reflected by fasting blood glucose2.
In another study carried out in New York hospital on
NIDDM patients, it was found that hyperglycemia plays
an important role in creating the ionic basis of
hypertension in diabetes mellitus4. Alterations of cell
ion content have been reported acutely after oral
glucose ingestion, and chronically in subjects with
hypertension and NIDDM4.

2. Diabetes mellitus is a heterogeneous metabolic
disorder characterized by persistent hyperglycemia.
The syndrome may develop due to defective insulin
secretion (insulin deficiency) or insulin action (insulin
resistance) or both. Insulin deficiency and insulin
resistance might be the consequence of one another,
and of these two factors, which appears earlier is still
not known. However, it is now well established that
an impairment of insulin secretion from the pancreatic
B-cells constitute an important pathophysiological
factor in the development of diabetes mellitus.
Materials and Methods
In the present study, 30 treated diabetic patients of
both sexes, aged between 23 to 27 years, and having
BMI of 17.9 to 22.54 kg/m2 were randomly selected
from the outpatient department, BIRDEM and were
included in Group II. They were further subgrouped on
the basis of their serum fasting glucose levels into Gr
IIa: FSG from 6 to 10 mmol/l, n=10; Gr IIb: FSG from
10 to 15 mmol/l, n=10; & Gr IIc: FSG > 15 mmol/l,
n=10. Thirty age and sex matched healthy subjects
with BMI of 20.55 to 25.49 kg/m2 were studied as
control and included in Group I having no family history
of diabetes up to second generation.
Detailed sociodemographic data, family history of
diseases, medical history, physical and clinical
examinations were done on the very first day of visit
and recorded in a predesigned questionnaire. All the
biochemical tests were done in the Department of Cell
and Molecular Biology, BIRDEM. Blood glucose level
was measured by Glucose Oxidase method5. Serum
electrolytes Na+, K+, Mg2+ and Ca2+ were measured
by Ion Sensitive Electrode Method by using NOVA-8
analyzer6. Unpaired Students ‘t’ Test and Pearson’s
correlation coefficient analysis were done between and
amonggroupsandp<0.05wasacceptedasstatistically
significant. All calculations were done using SPSS
version 11.5 Statistical Package for Windows.
Results
Age, BMI, serum fasting glucose level and blood
pressure of different groups are shown in Table I.
Table II shows that serum Na+ and Mg2+
concentrations were lower and serum K+ concentration
was higher in treated diabetic patients compared with
those of control (p<0.001). On the other hand, serum
Ca2+ concentration showed no significant difference
between the two groups.
Table III reveals that serum Na+ and Mg2+
concentrations were significantly lower and serum K+
concentration was significantly higher in Gr IIc
compared to Gr IIa but there were no significant
difference of them between Gr IIa and Gr IIb. There
was no significant difference of serum Ca2+ among
the three groups.
Table I
General features of the study subjects (mean ± SD)
Groups Age BMI FSGL SBP DBP
(years) (kg/m2) (mmol/l) (mmHg) (mmHg)
I (n = 30) 25.97±2.03 23.02±2.47 4.23±0.67 110±8 72±9
II (n = 30) 24.83±1.88 20.22±2.32 13.20±5.11 112±9 70±8
BMI = Body Mass Index, FSGL = Fasting Serum Glucose Level, SBP = Systolic Blood Pressure, DBP = Diastolic Blood
Pressure. Group I = Control; Group II = Treated Diabetic Patients; n = number of subjects
Table II
Serum electrolytes of the study groups (mean ± SD)
Groups Na+ K+ Mg2+ Ca2+
(mmol/l) (mmol/l) (mmol/l) (mmol/l)
I (n = 30) 146±3 3.5±0.4 0.48±0.04 1.07±0.06
II (n = 30) 141±3 4.3±0.6 0.43±0.06 1.02±0.09
Group I = Control; Group II = Treated Diabetic Patients; n = number of subjects
Comparative Study of Serum Electrolytes among Treated Diabetic Subjects Ruksana Karim et al
123

3. Table-III
Serum electrolytes in treated study subjects in different groups depending on serum fasting glucose
(mean ± SD)
Groups Na+(mmol/l) K+(mmol/l) Mg2+(mmol/l) Ca2+(mmol/l)
Gr IIa (n = 10) 144±2 4.17±0.44 0.47±0.04 1.02±0.10
Gr IIb (n = 10) 142±3 3.85±0.42 0.42±0.03 1.03±0.11
Gr IIc (n = 10) 140±3 4.79±0.52 0.39±0.06 1.00±0.08
t/p values
Gr IIa vs Gr IIb 1.89/0.075 1.64/0.117 2.35/0.03 -0.306/0.76
Gr IIa vs Gr IIc 3.37/0.003 -2.84/0.01 2.78/0.01 0.48/0.63
Gr IIb vs Gr IIc 1.28/0.21 -4.39/0.0001 1.01/0.32 0.81/0.42
Differences between the groups were calculated by Unpaired Students ‘t’ Test.
Gr IIa: Patients having FSG 6-10 mmol/l; Gr IIb: Patients having FSG 10-15 mmol/l; Gr IIc: Patients having FSG
>15 mmol/l; n = number of subjects
Table-IV
Correlation study between fasting serum glucose levels and electrolytes of the study subjects
Subjects Na+ K+ Mg2+ Ca2+
r p r p r p r p
Gr IControl subjects (n = 30) 0.289 0.122 0.231 0.219 -0.041 0.829 0.258 0.169
Gr IITreated diabetic subjects (n=30) -0.452 0.012 0.463 0.010 -0.477 0.008 -0.234 0.214
Pearson’s bivariate correlation coefficient analysis (r); p<0.05 is significant.
Correlationanalyses weredonebetweenfastingserum
glucose and serum electrolytes among control
subjects (Gr I) and treated diabetic subjects (Gr II) as
shown in Table IV. No correlation was observed in
control subjects. Na+ showed a significant negative
correlation with fasting serum glucose (p<0.05). K+
showed a significant positive correlation with fasting
serum glucose (p<0.01). Mg2+ also showed a
significant negative correlation with fasting serum
glucose (p<0.01). Ca2+ did not show any significant
relationship with fasting glucose levels.
Discussion
The ionized forms of Na, K, Mg and Ca are biologically
the most relevant fractions of these electrolytes7 and
their levels are critically maintained in the body fluids.
In the healthy (control) subjects, serum Na+, K+, Mg2+
andCa2+ levelswerefoundtobe146±3mmol/l,3.5±0.4
mmol/l, 0.48±0.04 mmol/l and 1.07±0.06 mmol/l
respectively. It can be seen that the mean value of
ionized sodium is at the extreme upper level and that
of ionized potassium is at the lowest level of reference
ranges reported for European healthy population using
the same technique (Na+: 139±2.33 mmol/l; K+:
3.6±0.8 mmol/l respectively). However both the Ca2+
and Mg2+ values were marginally below the
correspondingreferenceranges(1.13±0.09mmol/land
0.53±0.12mmol/lrespectively)forthesamepopulation.
Although a larger population based values of these
electrolytes are required to establish the reference
ranges of these ions in the plasma of our population,
the result may, at the least, indicate the importance
of establishing our own reference values.
Electrolyte imbalances may complicate both acute
and chronic metabolic abnormalities of diabetes. Thus
it is of utmost importance to have baseline data for
diabetic patients regarding their plasma electrolytes.
The data of the present study correspond to most of
the results generated for other population - significant
hyponatremia and hypomagnesemia paralleled by
hyperkalemia and no change in serum ionized
calcium1,2,3. The above findings are reinforced by
J Uttara Adhunik Med. College Vol. 03, No. 02, July 2013
124

4. parallel measurements using an up to date Ion
Sensitive Electrode Technology.
It is evident that there is a stepwise change in the
degrees of hyponatremia, hypomagnesemia and
hyperkalemia with the progressive rise of serum
glucose. The continued change of up to 15 mmol/l
glucose indicates that it is not a saturable system at
this level of serum fasting glucose. The notion is
supported by appropriate significant correlations –
negative for Na+ (r = -0.42; p<0.05) and Mg2+ (r = -
0.477; p<0.01), and positive for K+ (r = 0.463; p<0.01)
- with serum fasting glucose in the study subjects.
These correlations also correspond to the results of
studies done in other populations1,3. Serum Ca2+
showed no significant correlation with serum fasting
glucose (r = -0.234; p>0.05).
It has been suggested that increased excretion of
Mg2+ in response to hyperglycemia may be postulated
as a cause for hypomagnesemia7,8. The reasons for
understand hyponatremia and hyperkalemia are still
not definitely; however depression of Na+-K+ ATPase
may be an important cause as postulated by others9.
It is to be noted that this diabetic population is
relatively free from factors like obesity,
hyperinsulinemia and dyslipidemia which may affect
electrolyte levels. So the results may truly reflect the
changes induced by hyperglycemia.
The tight regulation of Ca2+ in the face of varying
degrees of hyperglycemia is interesting to be noted.
The ion did not show any significant correlation with
glucose level demonstrating the maximum attempt of
the homeostatic mechanism to maintain its level within
normal range.
Conclusion
The present study reveals that the serum Na+, K+
and Mg2+ levels are altered in diabetic patients
undergoing treatment with a reduction in Na+ and
Mg2+, increase in K+, and no change in Ca2+. It can
also be concluded from this study that in non-diabetic
young Bangladeshi population, as compared to the
reference ranges reported for the western population
using the same analytic technique, the value of Na+
is at the extreme upper level, that of K+ is at the lowest
level, and those of Ca2+ and Mg2+ are marginally below
the range. It may be added that serum glucose level
seems to be the predominant factor in determining
the degree of extracellular ionic changes in diabetes
mellitus. Further in-depth studies including intracellular
and urinary level measurements in different groups of
diabetic population should be done to have a better
understanding of the electrolyte status of the diabetic
patients in our country.
References
1. HerchuelzA and Malaisse WJ. Regulation of calcium fluxes
in rat pancreatic islets. In: dissimilar effects of glucose
and of sodium ion accumulation. J Physiol. 1980; 302:
263-280.
2. Lebrun P, Malaisse WJ and Herchuelz A. Na+
- K+
pump
activity and the glucose stimulated Ca2+
- sensitive K+
permeability in the pancreatic B-cells. Arch Biochem
Biophys. 1993; 300: 372-377.
3. Smith LH. Disorders of magnesium metabolism. In:
Wyngaarden JB, Smith LH, Bennett JC, editors. Cecil
Textbook of Medicine.19th
ed. Philadelphia: WB Saunders
Company; 1992. p. 1138-1139.
4. Grapengiesser E, Berts A, Shaha S, Lund PE, Gylfe E and
Hellman B. Dual effect of Na+
/K+
pump inhibition on
cytoplasmic Ca2+
oscillations in pancreatic B-cells. Arch
Biochem Biophys. 1993; 300: 372-377.
5. Olukoga AO, Erasmus RT and Adewoye HO. Erythrocyte
and plasma magnesium status in Nigerians with diabetes
mellitus. Ann Clin Biochem. 1989; 26: 74-77.
6. Yaqoob M. Water Electrolyte and Acid-Base Balance. In:
Kumar P, Clark MJ, editors. Clinical Medicine. 4th
ed.
Livingstone Hall: Branwall and Christopher; 1994:
494-497.
7. Lenive C and Coburn JW. Magnesium, the mimic/antagonist
of calcium. N Engl J Med 1984; 19: 1253-1254.
8. Valides RR. Zinc: prenatal point of view. Prog Food Nutr
Sci. 1992; 16: 279-306.
9. Tonyai S, Motto C, Rayssiguer Y and Heaton FW.
Erythrocyte membrane in magnesium deficiency.Am J Nutri.
1985; 4: 399.
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