diabetes research and clinical practice 108 (2015) 414–422
Contents available at ScienceDirect
Diabetes Research and Clinical Practice jou rnal hom ep ag e: w ww.e l s e v i er . c om/ loca te / d i ab r es
Progression from optimal blood glucose and pre-diabetes to type 2 diabetes in a high risk population with or without hypertension in Isfahan, Iran Mohsen Janghorbani a,b,*, Masoud Amini b a
Department of Epidemiology and Biostatistics, School of Public Health, Isfahan University of Medical Sciences, Isfahan, Iran b Isfahan Endocrine and Metabolism Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
article info
abstract
Article history:
Aim: To estimate the progression rates from normal glucose tolerance (NGT), isolated
Received 12 May 2014
impaired glucose tolerance (IGT), isolated impaired fasting glucose (IFG) and combined
Received in revised form
IFG/IGT to type 2 diabetes (T2D) in a high risk population with and without hypertension
3 September 2014
(HTN) in Isfahan, Iran.
Accepted 6 March 2015
Methods: During a mean (SD) follow-up period of 6.8 (1.7) years, 1489 non-diabetic first-
Available online 13 March 2015
degree relatives of patients with T2D with or without HTN were followed for the occurrence of T2D. At baseline and through follow-ups, participants underwent a standard 75 g 2-h oral
Keywords:
glucose tolerance test. Blood pressure was measured by standardised protocols and HTN
Diabetes mellitus
was defined according to the criteria of the JNC7.
Blood pressure
Results: The progression rate (95% confidence interval) from NGT, isolated IFG, isolated IGT,
Hypertension
and combined IFG/IGT to T2D was 10.0 (4.3, 19.6), 21.7 (9.5, 42.3), 28.2 (12.3, 54.7) and 64.7
Risk factors
(41.0, 96.4) per 1000 person-years in participants with HTN and 3.1 (1.5, 4.7), 16.3 (10.3, 24.2),
Diabetes progression
25.9 (17.0, 37.7) and 57.9 (46.1, 71.7) per 1000 person-years in participants without HTN based on 10,134 person-years of follow-up. Compared with individuals with NGT and without HTN, individuals with NGT and HTN, isolated IFG, isolated IGT, and combined IFG/IGT with or without HTN at baseline were more likely to progress to T2D. Compared with participants without HTN, individuals with concomitant HTN were not significantly more likely to progress to T2D. Conclusions: Compared with individuals without HTN, the presence of NGT, isolated IFG, isolated IGT, and combined IFG/IGT with concomitant HTN was not associated with higher likelihood of progression to T2D in high-risk individuals in Iran. # 2015 Elsevier Ireland Ltd. All rights reserved.
* Corresponding author at: Department of Epidemiology and Biostatistics, School of Public Health, Isfahan University of Medical Sciences, Isfahan, Iran. Tel.: +98 31 32334893; fax: +98 31 36682509. E-mail address: [email protected] (M. Janghorbani). http://dx.doi.org/10.1016/j.diabres.2015.03.002 0168-8227/# 2015 Elsevier Ireland Ltd. All rights reserved.
diabetes research and clinical practice 108 (2015) 414–422
1.
Introduction
Compared to individuals with normal glucose tolerance (NGT), individuals with pre-diabetes are at substantial risk of developing type 2 diabetes (T2D) [1]. The role of hypertension (HTN) as a risk factor for diabetes remains unsettled. HTN appears to be increased risk of T2D in most [2,3] but not all studies [4]. Although there are not many supporting evidences on the progression rate from NGT or pre-diabetes to T2D in individuals with or without HTN [5,6], the role of concomitant HTN and pre-diabetes as a risk factor for progression to T2D remains unsettled. Francis et al. [6] reported that pre-diabetic patients with concomitant HTN were significantly more likely to progress to T2D. A recent study performed in Chinese subjects revealed that individuals with impaired fasting glucose (IFG) were more likely to develop T2D if they were hypertensive [5]. However, while these two studies [5,6] referred to co-morbid HTN as a predictor of progression to T2D, it is likely that genetic factors also influence HTN and T2D. HTN and T2D have similar risk factors such as adiposity that are determined by genetic and early environmental influences. First degree-relatives (FDR) of patients with T2D which have a genetic basis are at higher risk of developing glucose intolerance and T2D [7,8] and might be more appropriate for testing this hypothesis. Studies also suggest that HTN and T2D run in families [9]. This may be due to shared environment and lifestyle or genetic. Information on the risk of progression from NGT and pre-diabetes to T2D in individuals with or without HTN in these high risk individuals is highly relevant as progression to T2D is preventable or delayed with lifestyle changes or pharmacological interventions [10–15]. The objective of this study therefore was to estimate the progression rates from NGT, isolated impaired glucose tolerance (IGT), isolated impaired fasting glucose (IFG) and combined IFG/IGT to T2D in a high risk Iranian population with or without HTN.
2.
Subjects and methods
2.1.
Data collection
This study was conducted within the framework of the Isfahan Diabetes Prevention Study (IDPS), an ongoing cohort in central Iran to assess the various potential risk factors for diabetes in subjects with family history of T2D (one of the main risk factors for diabetes). The study was established in 2003–2005 when 3370 (875 men and 2495 women) FDRs of a consecutive sample of patients with type 2 diabetes attending clinics in Isfahan Endocrine and Metabolism Research Center which is affiliated to Isfahan University of Medical Sciences, Iran, completed clinical and laboratory tests including standard 75 g 2-h oral glucose tolerance test (OGTT) and a questionnaire on their health status and on various potential risk factors for diabetes. Participants receive follow-up tests according to Standard of Medical Care in Diabetes [16] to update information on demographic, anthropometric, and
415
lifestyle factors and on newly diagnosed diabetes, IGT and IFG. Accordingly, if OGTT was normal at baseline; repeat testing was carried out at least at 3-year interval. Otherwise, repeat testing was carried out annually. The IDPS baseline methods have been described in detail elsewhere [17]. The participants included siblings and children of patients with T2D.
2.2.
Ascertainment of impaired glucose metabolism
Cases of NGT, isolated IGT, isolated IFG, combined IFG/IGT and diabetes were identified from baseline and follow-up OGTTs according to American Diabetes Association criteria [18]. Individuals who were not diabetic at baseline and who had at least one subsequent examination were included. Pregnant women and patients with type 1 diabetes were excluded. Among 3370 persons who participated at baseline, 308 subjects were excluded because of diagnosis of T2D at baseline and 1526 have no follow-up, and 67 with missing data leaving 1489 participants (361 men and 1128 women) with a mean (standard deviation [SD]) age 43.1 (6.5) (range 30–70) years for this longitudinal analysis, all of whom had at least one subsequent review during a mean (SD) follow-up period of 6.8 (1.7) (range 1–11) years. Attendees at the follow-up visit did not differ significantly from non-attendees regarding most baseline characteristics: age, height, weight, body mass index (BMI), waist circumference (WC), hip circumference (HC), waist-to-hip ratio (WHR) and levels of HbA1c, cholesterol, low-density lipoprotein cholesterol (LDLC), triglyceride, systolic and diastolic blood pressure (BP) and obesity. However, non-attendees had slightly lower fasting plasma glucose (FPG) (94.7 mg/dl versus 95.7 mg/dl, P < 0.05), and plasma glucose (PG) at 30 min. (138.7 mg/dl versus 145.6 mg/dl, (P < 0.001), 60 min. (141.1 versus 151.0, P < 0.001) and 120 min. (111.2 mg/dl versus 120.6 mg/dl, P < 0.001), but higher levels of high-density lipoprotein cholesterol (HDLC) (46.4 mg/dl versus 45.0 mg/dl, P < 0.05).
2.3.
Procedures
Information on age, gender, body size, HbA1c, cholesterol, LDLC, HDLC, triglyceride and BP, family and personal medical history was collected at the baseline and through follow-ups. The same methodology was used for both the prevalence and incidence studies. Participants reported to clinics in the morning after an overnight fast. Subjects were asked to abstain from vigorous exercise in the evening before and in the morning of the investigations. Smokers were encouraged to abstain from smoking in the morning of the investigations. First on arrival at the clinic, the information given by the participants in the questionnaire on family history was verified. Then, with the subjects in light clothes and without shoes height, weight, waist, and HC were measured using standard apparatus. Weight was measured to the nearest 0.1 kg on a calibrated beam scale. Height, waist, and HC were measured to the nearest 0.5 cm with a measuring tape. Waist was measured midway between the lower rib margin and the iliac-crest at the end of a gentle expiration. HC was measured over the greater trochanters directly over the underwear. Resting BP was measured after subjects had been seated for 10 min by using a mercury column sphygmomanometer and
416
diabetes research and clinical practice 108 (2015) 414–422
appropriately sized cuffs, using standard techniques. FPG was measured using the glucose oxidase method. Subjects with FPG
Contents available at ScienceDirect
Diabetes Research and Clinical Practice jou rnal hom ep ag e: w ww.e l s e v i er . c om/ loca te / d i ab r es
Progression from optimal blood glucose and pre-diabetes to type 2 diabetes in a high risk population with or without hypertension in Isfahan, Iran Mohsen Janghorbani a,b,*, Masoud Amini b a
Department of Epidemiology and Biostatistics, School of Public Health, Isfahan University of Medical Sciences, Isfahan, Iran b Isfahan Endocrine and Metabolism Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
article info
abstract
Article history:
Aim: To estimate the progression rates from normal glucose tolerance (NGT), isolated
Received 12 May 2014
impaired glucose tolerance (IGT), isolated impaired fasting glucose (IFG) and combined
Received in revised form
IFG/IGT to type 2 diabetes (T2D) in a high risk population with and without hypertension
3 September 2014
(HTN) in Isfahan, Iran.
Accepted 6 March 2015
Methods: During a mean (SD) follow-up period of 6.8 (1.7) years, 1489 non-diabetic first-
Available online 13 March 2015
degree relatives of patients with T2D with or without HTN were followed for the occurrence of T2D. At baseline and through follow-ups, participants underwent a standard 75 g 2-h oral
Keywords:
glucose tolerance test. Blood pressure was measured by standardised protocols and HTN
Diabetes mellitus
was defined according to the criteria of the JNC7.
Blood pressure
Results: The progression rate (95% confidence interval) from NGT, isolated IFG, isolated IGT,
Hypertension
and combined IFG/IGT to T2D was 10.0 (4.3, 19.6), 21.7 (9.5, 42.3), 28.2 (12.3, 54.7) and 64.7
Risk factors
(41.0, 96.4) per 1000 person-years in participants with HTN and 3.1 (1.5, 4.7), 16.3 (10.3, 24.2),
Diabetes progression
25.9 (17.0, 37.7) and 57.9 (46.1, 71.7) per 1000 person-years in participants without HTN based on 10,134 person-years of follow-up. Compared with individuals with NGT and without HTN, individuals with NGT and HTN, isolated IFG, isolated IGT, and combined IFG/IGT with or without HTN at baseline were more likely to progress to T2D. Compared with participants without HTN, individuals with concomitant HTN were not significantly more likely to progress to T2D. Conclusions: Compared with individuals without HTN, the presence of NGT, isolated IFG, isolated IGT, and combined IFG/IGT with concomitant HTN was not associated with higher likelihood of progression to T2D in high-risk individuals in Iran. # 2015 Elsevier Ireland Ltd. All rights reserved.
* Corresponding author at: Department of Epidemiology and Biostatistics, School of Public Health, Isfahan University of Medical Sciences, Isfahan, Iran. Tel.: +98 31 32334893; fax: +98 31 36682509. E-mail address: [email protected] (M. Janghorbani). http://dx.doi.org/10.1016/j.diabres.2015.03.002 0168-8227/# 2015 Elsevier Ireland Ltd. All rights reserved.
diabetes research and clinical practice 108 (2015) 414–422
1.
Introduction
Compared to individuals with normal glucose tolerance (NGT), individuals with pre-diabetes are at substantial risk of developing type 2 diabetes (T2D) [1]. The role of hypertension (HTN) as a risk factor for diabetes remains unsettled. HTN appears to be increased risk of T2D in most [2,3] but not all studies [4]. Although there are not many supporting evidences on the progression rate from NGT or pre-diabetes to T2D in individuals with or without HTN [5,6], the role of concomitant HTN and pre-diabetes as a risk factor for progression to T2D remains unsettled. Francis et al. [6] reported that pre-diabetic patients with concomitant HTN were significantly more likely to progress to T2D. A recent study performed in Chinese subjects revealed that individuals with impaired fasting glucose (IFG) were more likely to develop T2D if they were hypertensive [5]. However, while these two studies [5,6] referred to co-morbid HTN as a predictor of progression to T2D, it is likely that genetic factors also influence HTN and T2D. HTN and T2D have similar risk factors such as adiposity that are determined by genetic and early environmental influences. First degree-relatives (FDR) of patients with T2D which have a genetic basis are at higher risk of developing glucose intolerance and T2D [7,8] and might be more appropriate for testing this hypothesis. Studies also suggest that HTN and T2D run in families [9]. This may be due to shared environment and lifestyle or genetic. Information on the risk of progression from NGT and pre-diabetes to T2D in individuals with or without HTN in these high risk individuals is highly relevant as progression to T2D is preventable or delayed with lifestyle changes or pharmacological interventions [10–15]. The objective of this study therefore was to estimate the progression rates from NGT, isolated impaired glucose tolerance (IGT), isolated impaired fasting glucose (IFG) and combined IFG/IGT to T2D in a high risk Iranian population with or without HTN.
2.
Subjects and methods
2.1.
Data collection
This study was conducted within the framework of the Isfahan Diabetes Prevention Study (IDPS), an ongoing cohort in central Iran to assess the various potential risk factors for diabetes in subjects with family history of T2D (one of the main risk factors for diabetes). The study was established in 2003–2005 when 3370 (875 men and 2495 women) FDRs of a consecutive sample of patients with type 2 diabetes attending clinics in Isfahan Endocrine and Metabolism Research Center which is affiliated to Isfahan University of Medical Sciences, Iran, completed clinical and laboratory tests including standard 75 g 2-h oral glucose tolerance test (OGTT) and a questionnaire on their health status and on various potential risk factors for diabetes. Participants receive follow-up tests according to Standard of Medical Care in Diabetes [16] to update information on demographic, anthropometric, and
415
lifestyle factors and on newly diagnosed diabetes, IGT and IFG. Accordingly, if OGTT was normal at baseline; repeat testing was carried out at least at 3-year interval. Otherwise, repeat testing was carried out annually. The IDPS baseline methods have been described in detail elsewhere [17]. The participants included siblings and children of patients with T2D.
2.2.
Ascertainment of impaired glucose metabolism
Cases of NGT, isolated IGT, isolated IFG, combined IFG/IGT and diabetes were identified from baseline and follow-up OGTTs according to American Diabetes Association criteria [18]. Individuals who were not diabetic at baseline and who had at least one subsequent examination were included. Pregnant women and patients with type 1 diabetes were excluded. Among 3370 persons who participated at baseline, 308 subjects were excluded because of diagnosis of T2D at baseline and 1526 have no follow-up, and 67 with missing data leaving 1489 participants (361 men and 1128 women) with a mean (standard deviation [SD]) age 43.1 (6.5) (range 30–70) years for this longitudinal analysis, all of whom had at least one subsequent review during a mean (SD) follow-up period of 6.8 (1.7) (range 1–11) years. Attendees at the follow-up visit did not differ significantly from non-attendees regarding most baseline characteristics: age, height, weight, body mass index (BMI), waist circumference (WC), hip circumference (HC), waist-to-hip ratio (WHR) and levels of HbA1c, cholesterol, low-density lipoprotein cholesterol (LDLC), triglyceride, systolic and diastolic blood pressure (BP) and obesity. However, non-attendees had slightly lower fasting plasma glucose (FPG) (94.7 mg/dl versus 95.7 mg/dl, P < 0.05), and plasma glucose (PG) at 30 min. (138.7 mg/dl versus 145.6 mg/dl, (P < 0.001), 60 min. (141.1 versus 151.0, P < 0.001) and 120 min. (111.2 mg/dl versus 120.6 mg/dl, P < 0.001), but higher levels of high-density lipoprotein cholesterol (HDLC) (46.4 mg/dl versus 45.0 mg/dl, P < 0.05).
2.3.
Procedures
Information on age, gender, body size, HbA1c, cholesterol, LDLC, HDLC, triglyceride and BP, family and personal medical history was collected at the baseline and through follow-ups. The same methodology was used for both the prevalence and incidence studies. Participants reported to clinics in the morning after an overnight fast. Subjects were asked to abstain from vigorous exercise in the evening before and in the morning of the investigations. Smokers were encouraged to abstain from smoking in the morning of the investigations. First on arrival at the clinic, the information given by the participants in the questionnaire on family history was verified. Then, with the subjects in light clothes and without shoes height, weight, waist, and HC were measured using standard apparatus. Weight was measured to the nearest 0.1 kg on a calibrated beam scale. Height, waist, and HC were measured to the nearest 0.5 cm with a measuring tape. Waist was measured midway between the lower rib margin and the iliac-crest at the end of a gentle expiration. HC was measured over the greater trochanters directly over the underwear. Resting BP was measured after subjects had been seated for 10 min by using a mercury column sphygmomanometer and
416
diabetes research and clinical practice 108 (2015) 414–422
appropriately sized cuffs, using standard techniques. FPG was measured using the glucose oxidase method. Subjects with FPG
