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ORIGINAL ARTICLE
Year : 2009  |  Volume : 50  |  Issue : 1  |  Page : 14-17 Table of Contents     

The prevalence of prediabetes among hypertensive patients in Enugu, southeast Nigeria


Department of Medical Laboratory Sciences, Faculty of Health Sciences & Technology, College of Medicine, University of Nigeria, Enugu, Nigeria

Date of Web Publication16-Nov-2010

Correspondence Address:
I. S. I. Ogbu
Department of Medical Laboratory Sciences, Faculty of Health Sciences &Technology, College of Medicine, University of Nigeria, Enugu
Nigeria
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Source of Support: None, Conflict of Interest: None


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   Abstract 

Objective: To determine the prevalence of prediabetes among hypertensive patients under treatment.
Research Design: One hundred hypertensive patients under drug treatment, 40 men and 60 women, aged above 35years and 100 age and sex-matched apparently healthy subjects were used for the study. The patients were on aspirin, nifidepine, frusemide and felodipine as mainline drugs. Venous blood samples were collected after over-night fast and 2 hours after 75g dextrose ingestion.
Main Findings:Twenty-five patients, 10 males 25% and 15 females 25%, had prediabetes giving a prevalence of 25%. Fourteen of them (14%). 4 men and 10 women, had impaired fasting glucose only and 5 (5%) patients; 2 men and 3 women had unpaired glucose tolerance only. Six patients (6%) had both IFG and IGT. Unreported diabetes was detected in 14 patients (14%), among whom were 7 men and 7 women. Fifteen patients, (15%), had IFG only, and 5 (5%) patients had IGT only. The mean fasting plasma insulin of the patients was 22.2±19.6 μU/ml and the HOMA-IR was 5.1±4.5.
Conclusion: The prevalence of prediabetes among the patients did not exceed reported range but the percentage of unreported diabetes was high. The results highlighted the importance of screening for prediabetes in the hypertensive patient population of the study locality. However, there were no significant differences between the parameters of the patients with IFG and IGT, (p>0.05)

Keywords: Prediabetes, hypetension, impaired glucose tolerance, impaired fasting glucose, insulin resistance, HOMA-IR, unreported diabetes


How to cite this article:
Ogbu I, Neboh CI. The prevalence of prediabetes among hypertensive patients in Enugu, southeast Nigeria. Niger Med J 2009;50:14-7

How to cite this URL:
Ogbu I, Neboh CI. The prevalence of prediabetes among hypertensive patients in Enugu, southeast Nigeria. Niger Med J [serial online] 2009 [cited 2019 May 24];50:14-7. Available from: http://www.nigeriamedj.com/text.asp?2009/50/1/14/71931


   Introduction Top


Epidemiological studies have provided evidence for the co-existence of hypertension (HBP) and Diabetes Mellitus (DM) and possibly point towards a common predisposing or promotional genetic and environmental factors for both of them [1],[2],[3] . Both conditions are often seen together in metabolic syndrome [4],[5],[6] . DM has a prolonged intermediate phase known as prediabetes (PD) [7] characterized by impaired fasting plasma glucose, 5.6-6.9mmol/L and impaired glucose tolerance 2 hours after 75g glucose load, 7.8-11.0mmol/L. These conditions are known as unpaired fasting glucose (IFG) and impaired glucose tolerance (IGT) respectively. PD subjects do not manifest any symptoms of impaired glucose metabolism but are at increased risk of developing cardiovascular complications and DM [8],[9],[10],[11],[12],[13],[14] . As the prevalence and incidence of DM increase rapidly worldwide [15] so will the prevalence and incidence of PD increase also since the latter is a phase in the natural history of the former.

Among primary health care patients in Canada, a prevalence of 3.5% was reported [16] and 40% was reported among with polycystic ovarian syndrome [17]. A prevalence of 11.2% was repoted among adults aged 50-59 years [18] , 33% for those aged more than 70years [19] in American population.

Since lifestyle changes and drug treatment can slow down or even prevent progression to type 2 DM, screeening for PD in HBP makes sense more so as people with PD are at increased risk for the development of cardiovascular complications independent of progression to type 2 DM [8],[9],[10],[11],[12] . Chances of developing DM have been known to decrease by as much as 58% as a result of lifestyle changes [20],[21] . Identify HBP patient with PD can have important implications for the intnesity of treatment and resultant reduction in cardiovascular morbidity and mortality [14] . This study aims at determining the prevalance of PD as IFG and/or IGT and assessing the insulin resistance status, using the homeostatic assessment model of insulin resistance (HOMA-IR) of hypertensive patients under treatment.


   Materials and Methods Top


One hundred registered HBP patients, 40 men and 60 women, aged 35 years and above, of the University of Nigeria Teaching Hospital (UNTH), Ituku-Ozalla, in Enugu State of Southeastern Nigeria, were consecutively recruited for this study. They were all on combined anti-hypertensive therapy with aspirin, nifidepine, frusemide and felodipine as the mainline drugs. Without drug treatment, their diastolic and systolic Blood Pressure (BP) readings were repeatedly above 90mmHg and 140mmHg respectively. BP readings were done using the 1999 WHO/SH guidelines [22] . Known Dm subjects, patients with secondary high BP, pregnant women and patients below the age of 25 years were not included in the study. This is to avoid the influence of these factors on blood glucose.

One hundred age and sex-matched apparently healthy subjects, (40 men) recruited from the immediate community served as control. The Ethics Committee of the Hospital approved the study protocol and informed consent was obtained from all patients. Measurements of their demographic and anthropometric parameters; age (years), weight (kg), height (meters), waist circumference (WC) (cm) and hip circumference (cm) were taken. Their BP readings, as measured on the day of sample collection, were recorded. Body mass index (BM) (kg/ m 2 ) was calculated as weight in kg divided by square of height in meters, HOMA-IR as the product of fasting insulin in μ.7/m I and fasting plasma glucose in millimole/l divided by 22.5 and waist-hip ratio (WHR) as waist circumference divided by hip circumference.

Five millimeters of fasting blood samples were collected from the ante-cubital vein of the subjects and 2ml was discharged into a fluoride-oxalate bottle for fasting plasma glucose, (FPG) estimation and the rest into a plain bottle for insulin estimation. The subjects were given 75g dextrose in cold water and further 2ml blood sample collected after two hours of administration of sugar for glucose determination. Plasma glucose was assayed by the method of Trinder [23] and insulin by ELISA method using Syntron Bioresearch Microwell Insulin kit. All determinations were done within 24 hours of sample collection.

For statistical analyses, all the hypertensive subjects were grouped into five; patients, control, those with IGT, IFG and unreported DM. Analysis of variance (ANOVA) statistics was used to compare the mean values of the groups and Pearsons correlation statistic was applied to determine the relationship between the parameters. PD was diagnosed as fasting plasma glucose between 5.6 and 6.1 mmol/l and/or 2 hour post-prandial glucose between 7.8 and 11.Ommol/17 .


   Results Top


Twenty-five patients, 10 males (25%) and 15 females (25%), had PD giving a prevalence of 25% among the patients. Fourteen of the patients with PD (14%), (4 men) had IFG only and 5(5) patients (2 men) had IGT only. Six of the patients, (6%), had both IFG and IGT. Unreported DM was detected in 14(14%), of the patients (7 men) with fasting plasma glucose and/or 2 hour post load plasma glucose higher than 6.9 and/or 11.Ommolll respectively. Out of the 14 patients with unreported DM five had their 2 hour postprandial plasma glucose in the PD range. Among the controls, two persons had IGT while one person had IFG giving a prevalence of 3.0% for PD.

The hypertensive patients had significantly larger WC (96.74±12.84 cm, p<0.0001) higher WHR (0.8942 ± 0.048, p = 0.0003), FPG (5.21 ± 1.99 mmol/l, p = 0.0032) and 2-hour post prandial glucose, (2HPPG) (6.9 ± 3.3mmol/l, p = 0.0003) than the control (86.23 ± 8.24 cm), (0.8587± 0.03636), (4.1 ± 0.72mmol/1) respectively [Table 1]. There were no significant differences between the parameters of the male and female subjects within the same group. However, male hypertensive subjects had significantly higher WC (95.35 ± 10.4cm, p = 0.0028), larger WHR (0.902 ± .035, p=0.0003), FPG (5.6 ± 0.027, p=0.0361) and 2HPPG (7.5 ± 3.8mmol/l, p = 0.0057) than the male control subjects 86.18 ± 9.4 cm, 0.8594 ± 0.026, 4.2 ± 0.61mmol/l, 4.8 ± 0.59mmol/l respectively [Table 1] and [Table 2], [Table 3]. Similarly, female hypertensive subjects had significantly higher WC (97.67 ± 14.2 cm, p = 0.0067), WHR (0.8892± 0.055), FPG (5.0 ± 1.3mmo1/l, p=0.0129), 2HPPG (6.5 ± 2.8 mmol/l, p = 0.0133) than their control counterparts, 86.31 ± 6.8cm, 0.8577 ± 0.026, 4.0 ± 0.70mmol/l and 4.5 ± 0.86mmol/l respectively; [Table 1] and [Table 2].
Table 1: Comparing the anthropometric parameters of the hypertensive patients and controls.

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Table 2: Comparing the laboratory parameters of the hypertensive patients and controls.

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Table 3: Clinical Characteristics of the different groups of hypertensive patients and control.

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Patients with IFG had significantly higher BMI (30.73kg/ m 2 , p <0.05) and WC (101.14 ± 13.43cm, p = <0.05) than those with IGT, 27.79 kg/m 2 and 98.86 ± 11.74cm respectively. Anthropometric parameters did not show significant correlation with any of the laboratory parameters. However, BMI correlated with WC (p = 0.0019,) and WHR, (p = 0.0123). The mean fasting plasma insulin of the patients were 21.55 ± 19.43μ/Uml, men 18.08 ± 6.07μ/Uml, and women 21. 12 ± 12.65μ/Uml while those of the control were 21.57± 8.54μ/Uml, men 19.92 ± 10.63μ/Uml, and women 19.15 ± 5.51 μ/Uml (p > 0.05). The HOMA-IR of the patients were 5.1 ± 4.5, men 4.4 ± 2.5 and women 5.0 ± 3.1 while those of the control were 4.7 ± 2.9, men 4.4 ± 2.3 and women 3.4 ± 1.4, (p> 0.05). The patient with IFG had fasting plasma insulin of 20.2 ± 7.6μ/Uml and HOMA-IR of 5.4 ± 2.0 while the hypertensive patients with IGT had 19.3 ± 4.9μ/Uml and 5.2 ± 1.6 respectively. These values did not differ significantly either between the men and the women or between those with IFG and IGT (p> 0.05).


   Discussion Top


The prevalence of PD among the HBP patients of the UNTH was 25%. This is within the range of 25 - 47% reported by Govindarajan et al [24] . Shrestha et al reported a prevalence of 43% among hypertensive patients in urban Nepal [25] . Mills and Grant stated that 25% of the population was in state of relative insulin resistance which preceded type 2 DM [26]. A prevalence of 3.5% was reported among primary health care patients with illness in Canada [19] , and 40% of women with polycystic ovarian syndrome [20] . Although 25% of US adults were known to have PD, only an estimated 4% were aware of this [27],[28] . Awareness was not assessed in this study. However, lack of the knowledge of the existence of PD in an individual makes screening for the condition in the general population necessary.

Impaired fasting glucose was more prevalent among the patients 15%, than IGT (5%). This is contrary to the report of Shobha et al who recorded a prevalence of 9.7% for IFG and 15.6% for IGT in US adult aged 40 -74 years. Among overweight subjects aged 45 - 74 years, the prevalence of combined IFG and IGT in Penghu Islets of Taiwan was found to be 14.7% and 30.7% among the women and men within the age ranges of 40 - 49 years and 50 - 59 years respectively [29].

IGT was said to be more sensitive in detecting early dysregulation than IFG It reflects hepatic gluconeogenesis and slower uptake to glucose from blood into skeletal muscles and adipose tissue following a meal [30] . It is also independently associated with traditional microvascular complications of diabetes. IGT patients, however, will not always progress to diabetes since it is a dynamic and reversible state. Some will revert to normoglycaemia while a greater percentage may continue as such [30] . Six patients (6%) had both IFG and IGT. Eleven patients, therefore, had IGT in this study (5 IGT alone and 6 IGT plus IFG), and are at increased risk of progressing to type 2 DM and developing cardiovascular disorders.

A large number of the patients (14%) had unreported DM. This underscores the necessity for regular screening of HBP patients for DM. Them can HOMA-IR of the patients, (5.1 ± 4.5) is in the upper range of values reported for PD (4.3 - 5.2) with some definitely in the DM range, 8.3 - 9.5, due to the presence of the unreported DM subjects. The HOMUIA-IR of the control subjects was outside the range of values reported for White Americans, 2.1- 2.7 [31] . The prevalence of PD among the patients did not exceed reported value range but the percentage of unreported DM was high. The reasons may include ignorance and lack of affordable health services. The lack of correlation between the anthropometric parameters and the laboratory parameters indicates that it may not be possible to predict PD from knowledge of the former parameters. The patients did not differ significantly from the control in their BMI but not in elevated WC and WHR. The differences in the later parameters reflect in significantly elevated fasting and 2-hour post prandial plasma glucose of the patients. This shows that BMI is not a good index of obesity in this group of patients. Normal fasting insulin levels in the hypertensive patients reflect the fact that most of the patients could secret enough insulin to keep them in normogycaemic state in the absence of insulin resistance as shown by normal index of insulin resistance.

The study has highlighted the importance of screening for PD especially among HBP patients of the study locality. [32],[33]

 
   References Top

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