The findings of this study show that the students who were exposed to high RF-EMF had significantly higher HbA1c than the students who were exposed to low RF-EMF. Moreover, students who were exposed to high RF-EMFR generated by MPBS had a significantly higher proportion of diabetes mellitus relative to the students who were exposed to low RF-EMFR.
HbA1c is well recognized among clinicians as a marker of chronic hyperglycemia, increased HbA1c has also been regarded as an independent marker for diabetes mellitus [17
]. HBA1c has numerous advantages compared to the Fasting Plasma Glucose (FPG), including greater expediency, fasting is not mandatory, better pre-analytical stability and less day-to-day worries during a period of stress and illness. HbA1c has recently been endorsed as a diagnostic test for diabetes by the World Health Organization, the International Diabetes Federation, as well as the American Diabetes Association [12
FPG of 100 mg/dL or 5.6 mmol/L equals to an HbA1c of 5.4% and FPG of 110 mg/dL or 6.1 mmol/L is parallel to HbA1C of 5.6% [13
]. The normal cut-off point of HbA1c is equal to or less than 5.4%. Compared to the fasting glucose cut point of 100 mg/dL (5.6 mmol/L), the HbA1c cut point of 5.7% is more specific and has a higher positive predictive value to identify people at risk for development of diabetes. HbA1c levels below 5.7% may still be at risk to develop diabetes mellitus [13
]. Literature also indicates that subjects within the HbA1C range of 5.5%–6.0% have a five-year cumulative incidence of diabetes mellitus that ranges from 12% to 25% [19
]. In the present study, we found that the mean HbA1c for the students who were exposed to high RF-EMFR was 5.44% compared to the mean HbA1c for the students who were exposed to low RF-EMFR 5.32% (Table 1
4.1. RF-EMFR and HbA1c
The possibility of induction of biological and health effects by low-energy radiation emitted by MPBS remains a debatable issue. In spite of decades of research, there is still ongoing discussion about RF-EMFR and physiologically-relevant effects. Literature is available on the association of RF-EMF with headache, tension, and sleep disorder-like symptoms [1
]. In addition, studies have also shown that RF-EMFR has extensive damaging effects on the nervous system, cardiovascular, and male reproductive system [20
]. RF-EMFR also causes oxidative damage [21
] and cancer [22
Bieńkowski et al.
] conducted a study and measured the changes in the electromagnetic field intensity in a school building and its surrounding after the MPBS installation on the roof of the school. They found that the EMF intensity increased in the building and its surroundings after the MPBS installation. Shahbazi-Gahrouei [24
] conducted a cross-sectional study on people living near the mobile phone base transceiver stations (BTS). The authors reported that discomfort, irritability, nausea, headache, dizziness, nervousness, depression, sleep disturbance, memory loss, and decreased libido were statistically significant among the people living near the BTS antenna (less than 300 m distant) compared to those living far from the BTS antenna (more than 300 m). They suggested that cellular phone BTS towers should not be installed at less than a distance of 300 m to human population to minimize exposure.
Meo et al.
] determined the effects of exposure to RF-EMFR generated by mobile phones on fasting blood glucose in albino rats. The authors found that, Wister albino rats exposed to RF-EMF generated by mobile phone for more than 15 min a day for a maximum period of three months had significantly higher fasting blood glucose and serum insulin compared to the control group. Meo et al.
] also reported that increase in fasting blood glucose was due to insulin resistance. In the present study, we found that students who were exposed to high RF-EMFR generated by MPBS had significantly higher HbA1c (Table 1
) and a higher prevalence of type 2 diabetes mellitus (Table 2
) than the students who were exposed to low RF-EMFR.
Altpeter et al.
] reported that the incidence for diabetes mellitus was higher among the subjects living within a close radius of a shortwave transmitter in Schwarzenburg, Switzerland compared with a population living away from the a shortwave transmitter. There was a significant linear relationship between RF radiation exposure and prevalence of diabetes mellitus.
Jolley et al.
] exposed the islets of Langerhans from rabbits to low-frequency pulsed magnetic fields and noted a significant decrease in insulin release during glucose stimulation compared to controls. Similarly, Sakurai et al.
] measured the insulin secretion from an islet cell, exposed to low-frequency magnetic fields compared with sham exposure group. Insulin secretion was decreased by about 30% when exposed to low-frequency magnetic fields compared to sham exposure.
Li et al.
] exposed hepatocytes in vitro
to 50 Hz pulsed EMF noted a conformation change in the insulin molecule. The authors found a decrease in the binding capacity of insulin to its receptors compared with controls.
Congruently, Havas [30
] reported that exposure to electromagnetic pollution cause higher plasma glucose levels and may contribute to diabetes mellitus. Havas [30
] also concludes that decreased insulin secretion and reduced binding capacity of insulin to its receptors may explain the elevated levels of plasma glucose in subjects exposed to electromagnetic fields. Similarly, in the present study, we found that students who were exposed to high RF-EMFR generated by MPBS had significantly higher HbA1c and risk of type 2 diabetes mellitus than the students who were exposed to low RF-EMFR. Choi et al.
, 2011 [31
] reported that individuals with HbA1c ≤ 5.5 is a normal; 5.6 to 6.9 is impaired HbA1c or pre-diabetes, and HbA1c 7.0 considered as a diabetes. They also reported that HbA1c ≥5.6% have an increased risk for future diabetes. In our study, we found that students who were exposed to high RF-EMFR have significantly higher HbA1c than the mean HbA1c for the students who had been exposed to low RF-EMFR. Moreover, students exposed to high RF-EMFR have significantly impaired HbA1c (31.25%) than the students who exposed to low RF-EMFR (27.0%).
4.3. Study Strengths and Limitations
To our knowledge, no study exists yet to establish an association between the RF-EMFR generated by MPBS and HbA1c and risk of type 2 diabetes mellitus. We measured the levels of RF-EMFR inside the schools to determine the impact of RF generated by MPBS on HbA1c. In this study for subject selection criteria, we follow the American Diabetic Association guidelines, and considered age, race, ethnicity, anemia, and hemoglobinopathies into consideration while using the A1C to diagnose diabetes [32
]. Moreover, our study exclusion criteria and assays are highly standardized. The limitation of the present study is the involvement of male gender only because in Saudi Arabia there is no co-education system at schools, colleges, and university levels. This study is a relatively small sample size, and because of the cross-sectional design of the study we could not establish the causation.