This study is one of the few large national population-based studies that have provided latest evidence on the status of diabetes mellitus in east and southern Africa region in general, Malawi in particular. In 1960s, diabetes was not an important public health problem in Malawi and the prevalence, then, was less than 1%. Malnutrition, even in adults was the main problem where up one in three adults (36%) were under-nourished or underweight (body mass index <18.5 Kg/m2) [7–9]. However, this study, in agreement with other studies, demonstrated that epidemiological nutritional transition occurred in Malawi just like in other countries in east and southern Africa. Overweight and/ or obesity, not under-nutrition, is now a major public health problem in adults where up to one in five (21.9%) adults are overweight  and prevalence of diabetes increased from less than 1% as previously reported in 1960s to 5.6% in 2009 (this study).
This study also demonstrated that in Malawi, diabetes was just as common in rural as in urban areas and in men as in women. Apparently it was higher in rural than urban areas, 5.4% (95% CI 2.4%-8.4%) vs 4.4% (95% CI 2.8-5.9%), in men than in women, 6.5% (95%CI 2.6%-10.3%) vs 4.7% (95% CI 2.7%-7.0%) but the differences were not statistically significant (p >0.05). Number of participants that were tested for fasting blood glucose was relatively smaller in urban than rural (371 vs 2685). This may have influenced the results. However, it has also be shown that hypertension, tobacco smoking and alcohol consumption were more frequent in rural than urban [11, 13, 14]. This is in agreement that non-communicable diseases in general, diabetes in particular should no longer be considered as diseases of the “affluent, urban or the west” . Other studies also reported similar findings that prevalence of diabetes was similar in men and women and impaired fasting blood glucose was higher in men than women . Promotion of healthy lifestyles and community awareness on diabetes should therefore target both men and women, urban and rural population.
In Malawi, complications of diabetes are common, particularly micro-vascular with prevalence of nephropathy, retinopathy and neuropathy of 34.7%, 34.7% and 46.4% respectively and control of glycemia and hypertension are poor . However, there are well structured and utilised community outreach clinic programmes. These could be made more comprehensive by adding diabetes screening, treatment and follow-up to the package of services being offered. Guidelines from WHO package for essential non-communicable disease (WHO-PEN) could be used in implementing diabetes screening, treatment and follow up programme. The WHO PEN primary health care approach has been recommended as one of cost-effective approaches for delivering interventions for chronic non-communicable diseases including diabetes in resource-poor settings [18–20].
Limitations of the study
Over-representation of females (70.2%) was one of the limitations of this study. However, it was unlikely that this had an influence on the results because data were weighted (standardised) for age and sex to national population. The over representation of females was not by study design because at household level, eligible participants were randomly selected using the Kish sampling method built-in the PDAs. Refusals/non-availability (though relatively small, 245 (5%) out of 5,451 eligible participants), was another limitation of this study. Specifically, males aged 25–34 years were the ones that were under-represented based on 2008 National Statistical Office population figures (42.5% vs 47.5%, p < 0.05). The under representation of men in this age group was due to some being away from home at the time of the survey. It was not known if this group had different survey characteristics. All the other age groups were representative of the national population. There were no differences in the refusal/non-availability between males and females and no replacements were made. About 88% of all the 3,056 participants that were tested for fasting blood glucose were from rural areas. This was not due selection bias but was in line with the population distribution in Malawi which is 85% rural .
The other limitation was that the Accutrend Plus machines (Roche, Mannheim, Germany) used this study for blood glucose testing were not standardized, quality controlled and capillary was not compared with venous plasma blood tests. However, the machines were calibrated every day using the glucose control strips as per instructions on the use of machines. Diagnosis of diabetes was based on fasting glucose test only. Without oral glucose tolerance test (OGTT) results, the estimated prevalence of 5.6% could be lower than the real prevalence.
Not all participants who consented and adhered to fasting were tested for blood glucose (number consented and adhered to fasting 5023, number tested 3056 (60.8%)). Technical factory fault of the biochemistry machines (Accutrend plus®) led to about 40% of the participants who gave their informed consent and adhered to fasting advice not to be tested. Two machines were sent back to the manufacturer (Roche). It was uncertain whether the failure to measure fasting blood glucose in all the participants who consented had an influence on the results. The curtailment of testing affected men, women and all age groups equally. Based on number of participants and their ages, the available results for each measurement were standardised for age and sex to the national population. The findings presented in this paper were therefore age-sex adjusted estimates. Nevertheless this population based study captured fasting blood glucose tests for over 3000 adults.