The sex distribution was similar between rural and urban individuals, with a female predominance. Although our study was not a prevalence study, differences in diabetes prevalence by sex have been reported to be variable depending on the population and setting . In some African populations, men are reported to be more affected than women , and women are reported to be more affected than men in other populations . In Cameroon, a homogenous sex distribution has been reported in rural populations, while in urban individuals, a female predominance was noticed . This variability in the sex-specific prevalence of diabetes might be related to differences in exposure to the risk factors for diabetes by sex; for example, the Rwanda NCD risk factors survey revealed that obesity and overweight are more prevalent in women than in men . This variability implies the need for specific population-based assessments of sex differences in terms of diabetes burden for targeted and need-based interventions to address the diabetes burden.
We found that diabetes was diagnosed at a younger age in our study population, which was most noticeable in rural individuals. Furthermore, rural residents were younger at the time of study enrolment. The age distribution among rural residents was consistent with patterns reported in other African populations [1,23] and in a south Asian population , and the age distribution was inconsistent with the findings in Western and urban African populations, in which larger proportions of older people were found among people with diabetes [23,25]. The age distribution among rural and LMIC populations in general might be explained by higher proportions of misclassified type 1 diabetes or so-called “malnutrition-related diabetes”, emerging atypical diabetes subtypes in underserved settings whose onset has been reported to be in the second and the third decade of life [26–28]. However, the higher proportion of diabetes in rural younger age individuals could also be explained by the poorer survival rate in more disadvantaged populations [29,30], which could lead to short life expectancy in individuals with diabetes living in poverty .
Most rural residents reported low-income work, limited access to running water and electricity, the use of herbal medicine for high blood glucose symptoms and less fruit and vegetable consumption. We did not explore the association of socio-economic condition with diabetes prevalence. At later stages of the epidemiologic transition, low socio-economic status was associated with an increased risk of NCDs such as diabetes mellitus, cancers and cardiovascular diseases . Poverty and food insecurity might contribute to the increasing prevalence of diabetes in some rural African settings in which diabetes prevalence is reported to exceed the diabetes prevalence in urban areas . In addition to the fact that poverty might contribute to the onset of diabetes potentially through foetal and childhood under-nutrition or obesity in later life, poverty is reported to be a factor related to unequal access to care . More importantly, even if there was no difference in health insurance coverage and there were dedicated diabetes clinics in rural hospitals in our population, poverty would make it more difficult for people with diabetes to keep themselves healthy: access to a healthy diet, electricity, a refrigerator to store insulin, and running water to keep injection sites clean as well as the ability to travel for specialist care, such as eye care. The impact of poverty and its consequences on the diabetes burden should be explored further in low-income countries.
We found that traditional risk factors for type 2 diabetes, such as family history of diabetes, obesity and physical inactivity, were less prevalent among rural individuals. Central obesity was prevalent in both groups but was less common in the rural group. This result is consistent with the findings of other reports from low-income countries in which the increasing prevalence of diabetes did not match the low prevalence of common risk factors for diabetes [24,34,35]. This finding means that there might be other factors contributing to the increase in diabetes prevalence in low-income settings. We found a higher prevalence of reported childhood under-nutrition among rural than among urban residents. It has long been suggested that chronic under-nutrition is associated with impaired insulin secretion . In addition, inflammatory markers have been reported as risk factors for type 2 diabetes , and they might contribute to the burden of diabetes in the poorest individuals in a population given that poverty is known to be associated with chronic infections such as tuberculosis, human immune-deficiency virus and other infections. To our knowledge, childhood under-nutrition as a risk factor for diabetes in adulthood has been given less attention in Sub-Saharan Africa, where its prevalence is reported to be high, especially in East Africa , where evidence suggests that the prevalence of diabetes in the poorest population is exceeding the prevalence in less poor populations . In urban settings, traditional risk factors remain the main drivers of the rapid increase in diabetes [19,20].
We observed an unusually high prevalence of type 1 diabetes among our study participants, particularly among rural dwellers. Furthermore, most participants, particularly those from rural areas, reported insulin requirements from diagnosis. The over-representation of type 1 diabetes could reflect the limitation of clinic-based nature of the study; people with type 2 diabetes might have participated in fewer clinic visits or received their care in other settings. In our case, people with diabetes are given appointments to attend the NCD clinics on a monthly basis for prescription renewal and follow up, with active retrieval of those who were lost to follow-up, regardless of the type of diabetes. Furthermore, we recruited participants in various health facilities on different diabetes clinic days over a whole year to overcome potential selection bias. Diabetes classification is usually based on clinical presentations in our clinics, and atypical diabetes with type 1-like phenotypes such as MRDM and ketosis-prone type 2 diabetes could have been misclassified as type 1 diabetes.
Although our study population was uniformly well covered by medical insurance, more rural individuals than urban participants reported severe hyperglycaemia at diagnosis and use of herbal medicine, and their diabetes was less controlled. Limited access to diabetes care, easy accessibility to traditional healers, lack of resources and frequent lack of stock of modern diabetes drugs have been reported to be the reasons for herbal medicine use and poor quality of diabetes care in LMICs [39,40]. There is a need to identify other barriers to quality diabetes care in the setting in which universal medical coverage is maximized and diabetes care decentralization to lower levels of the health system is established to improve equitable access to care.
The characteristics of people with diabetes in rural settings, such as low socio-economic conditions, young age of onset, lower prevalence of traditional risk factors for type 2 diabetes, higher prevalence of reported childhood under-nutrition and an unusually high prevalence of type 1 diabetes, imply that contextualized interventions are warranted to alleviate the burden of diabetes on the poorest people. Under-nutrition and over-nutrition as well as poverty might play an important role in the burden of diabetes in LMICs. Further studies are required to assess risk factors for diabetes in rural and low-income settings and to identify effective interventions to inform guidelines to prevent and treat atypical diabetes in rural LMICs.