Department of Nephrology, Riyadh Armed Forces Hospital, Riyadh, Saudi Arabia
Exercise is lacking in urban dwellers ... hence the incidence of ailments is high among city dwellers ... and in correlation with these high incidences, their need for the (medical) profession rises.
Al Muqaddama pp. 739742
Ibn Khaldoun,
Arab Sociologist and Historian (13321406)
Diabetes in the Saudi population
The prevalence of diabetes mellitus (DM) in the Saudi population is high and 90% of diabetics suffer from Type II DM. An epidemiological study of Saudi subjects aged 15 years or older, from different regions of the kingdom found that the age-adjusted prevalence of DM (using WHO criteria) was higher in urban areas (males 12%, females 14%) than rural areas (males 7%, females 7.7%) [1]. The highest prevalence was in urban females aged 5160 years (49%). In rural females of similar age the prevalence was 29%. Some 56% of those found to be diabetic in this survey had no prior knowledge that they had DM. In another survey, it was found that 17% of those aged 30 years or older had DM [2]. These figures compare to 3.1% in the USA (1993). The incidence in African American males and females, however, is two- and four-fold, respectively, that in Caucasians and is 70% in adult Pima Indians [3].
Obesity in the Saudi population
Among 9061 school children (aged 618 years) studied [4], a prevalence of obesity of 15.8% was found. The highest incidence of 18% was found in Riyadh (the capital) and the lowest in Sabea (11.1%), a small rural town in the south of the country. In a review of obesity prevalence in the Arab world [5] it was concluded that one-third of Arabs are obese as defined by a body mass index of 30 kg/cm2.
Among Saudi adults [6], 20 years or older, the overall prevalence of obesity was 22.1%. In males and females the prevalence was 17.8% and 26.6%, respectively, being higher in urban areas and increasing with age.
Obesity predisposes to insulin resistance and development of Type II DM. However, different ethnic groups seem to have varying risks with obesity. For example, in a follow-up study of 16 years, the age-adjusted incidence of developing DM was twice as much in black women than in white women (15% vs 7%) and one-and-a-half times higher in black men than in white men (10.4% vs 6.9%). Obesity in blacks predisposes to DM more than a similar degree of obesity in whites [7].
The Saudi population is a young population (60% are 20 years or younger). It is, therefore, anticipated that the prevalence of DM will increase rapidly in the near future and become among the highest in the world, especially with the high prevalence of obesity in school children. Some estimate that it will be 4050% in 2020.
The thrifty gene hypothesis could provide a plausible explanation for this dramatic rise in DM in Saudi Arabia. There has been increasing affluence in the Arabian Gulf countries associated with a massive increase in personal income over the last few decades. (The highest increase compared to any other country in the world.)
The energy intake (Kcal/day) has increased from 86% of recommended daily allowances (RDA) in 19611963 to 140% of RDA in 1995. The protein intake has increased from 91% of RDA to 162% over the same period. For women, the increases in energy and protein intakes were more pronounced, being 177% and 205%, respectively, of RDA in 1995 [8]. The changes in dietary habits that occurred in 20 years in the Kingdom of Saudi Arabia (KSA) took 137 years in Japan and 200 years in UK [8]. The percentage of family households owning a car in the 1960s was less than 5%, now the figure is 84%.
It should be noted that first cousin marriages are very common in KSA (accounting for 52% of all marriages). This could also be a factor in the increased prevalence of DM.
Diabetic nephropathy in Saudi Arabia
There are no data available on the incidence of diabetic renal disease in Saudi diabetics. What is known is that the vast majority of Saudi diabetics entering dialysis (96%) are of Type II. In a study of a diabetic outpatient clinic, 12.8% of patients had dipstick proteinuria and of the remaining patients 41.3% had microalbuminuria [9]. Appropriate methodology was used to exclude other causes of proteinuria. Of Caucasians with microalbuminuria, 2040% develop overt nephropathy over a 6-year period whereas 3740% of Pima Indians do so over 45 years [10]. If Saudi diabetics behave in a similar fashion as Pima Indians, with aggressive course of their diabetes, as seems the case (see below), this would indicate that we are going to face a medical catastrophe in our dialysis units as stated by Ritz et al. [11]. Indeed, we are already seeing this (see below).
The rate of progression of renal disease in diabetics differs from one ethnic group to another. British Asians have a more rapid course than Caribbeans or Caucasians [12]. The authors speculate that there may be racial differences in renoprotection by antihypertensives. We have no accurate data regarding the course of diabetic renal disease in the Saudi population.
We followed 28 patients with Type II DM complicated by diabetic nephropathy (indicated by presence of normal size kidney, presence of diabetic retinopathy and proteinuria, and confirmed by renal biopsy). The mean plasma creatinine in these patients at the start of observation was 180±64.7 µmol/l. Mean age was 61.2 years (±7.4). There were 16 males and 12 females. Twenty-four (85.9%) had progression of their renal disease over 19.7±9.4 months of follow-up. Of these 24, 12 required dialysis (50%) after a mean follow-up period of 18 months. The remaining patients doubled their creatinine (from a mean of 180.2 to a mean of 349.1±149) over a 19.7-month period. Thus, of the 28 patients who began the study, 42.8% became dialysis dependent and 42.8% doubled their creatinine; only 15% had a stable course (Al-Khader, in preparation).
This is a small group and the results require confirmation. Moreover, the study group was elderly and age in itself predisposes to faster progression. If the results are confirmed with future studies, the progression of Type II DM is alarmingly fast in Saudi patients. The difference between those who went on to dialysis and those who remained off dialysis was seen in the baseline creatinine of 244.2±67.2 and 138.2±46.4, respectively, (P=0.01) and histological scoring.
The same group of patients who underwent renal biopsy and scoring system was used to assess the severity of the histological changes (Kfoury, abstract book, Nephrology in the New Millennium, Riyadh 2001), using 0 to xxx scoring system for changes in eight different parameters. The severity was then expressed as mild, moderate or severe. Twenty six per cent of patients graded as moderate and 46% of patients graded as severe required dialysis within 6 months.
Diabetic nephropathy in end-stage renal disease patients
In their review Ritz et al. [11] pointed to the enormous impact diabetes has on renal services on a global scale. Virtually all countries with registers have reported a massive increase in the incidence and prevalence of diabetic nephropathy in their dialysis populationsome countries (e.g. USA) more than others (e.g. France) and some ethnic groups (e.g. African Americans, American Indians) more than others (e.g. Caucasians). This increase is due to an actual increase in prevalence of DM, increasing age of dialysis population (hence of DM) and better survival of patients with DM, thus allowing them to develop diabetic nephropathy. We faced a similar experience in our patients in KSA [13].
In 1982, there were 370 patients receiving dialysis in KSA, in 1999 the number increased to 5706, with 2084 new patients entering dialysis in 1999 alone (SCOT annual report 1999). The mean age increased from 37.9 to 51.3 years, respectively. Moreover, the percentage of patients aged over 50 years in 1999 was 59% compared to only 10% in 1982. In the early 1980s, our unit reported DM as a cause of end-stage renal disease in only 4% of the patients. In our unit the incidence of DM among the patients admitted to dialysis in 1999 was 40.5% [13]. This compares to 36.3% in USA (1993) (being highest in American Mexicans and blacks), 24% in Canada, 14% in Australia, 17% in Europe and 28% in Japan [3].
Of all diabetics entering dialysis, noninsulin-dependent DM accounted for 96% in our unit compared to 77% in African Americans, 42% in white Americans, 61% in Australians, 43% in Europeans and 95% in Pima Indians [3].
With increasing age and prevalence of DM as the cause of renal disease we have seen a rise in the mortality rate over the last 20 years. In 1984, we reported a mortality rate of 8% over a 5-year period. In those who died, the mean age was 62.3 years (as compared to mean age of all the dialysis patients of 51.3 years); 60.5% of the expired patients had DMthe cause of death was cardiovascular disease in 48%, sepsis in 38% and gastrointestinal bleeding in 14% [13]. The mortality rate in elderly diabetic patients on dialysis is known to be high and five-year survival as low as 6% has been reported [11].
The implications of this increased prevalence of DM amongst the dialysis population in KSA include [13]:
This is particularly sad since many diabetic complications are readily preventable by glycaemic control, blood pressure control and treatment of dyslipidaemia as well as control of obesity and exercise [3,11].
Post-transplant diabetes
In a study of 1112 post-transplant patients from two major transplant centres, we found the prevalence of DM to be 22.3% [15]. Other similar studies from KSA have shown the incidence to be between 17% and 25%. There are also similar reports from other international centres. The two significant differences which were found between those who developed diabetes and those who did not were age (46.4 and 36 years, respectively; P=0.02) and weight (70.2 and 66.1 kg, respectively; P=0.03).
The vast majority of diabetics entering dialysis in KSA are elderly (62.1 years) and have comorbid conditions [13], hence our experience with transplanting diabetic patients is very limited. In the few transplants undertaken, results were comparable to non-diabetics and the prognosis is much better than that for diabetics on dialysis. Similar results are described by Hirschl from Vienna [16]. However, it should be pointed out that we are highly selective and only transplant younger diabetics who undergo extensive investigations, including coronary angiography, to exclude comorbid conditions.
Finally, we have also reported full-blown diabetic nephropathy with nodular sclerosis in patients with de novo diabetes after transplantation and no diabetic retinopathy [17].
Notes
Correspondence and offprint requests to: Dr Abdullah A. Al-Khader, Department of Nephrology, Riyadh Armed Forces Hospital, PO Box 7897, Riyadh 11159, Saudi Arabia. Email: aaalkhader{at}yahoo.com
References
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