People who are already obese before they are diagnosed with type 2 diabetes have a significantly increased risk of developing microvascular complications in the course of the metabolic disease. This is the conclusion of an observational study based on data collected in the EPIC Potsdam cohort (European Prospective Investigation into Cancer and Nutrition). Macrovascular complications, on the other hand, seem to be hardly influenced by weight.
Overweight and obesity are among the most important risk factors for the development of type 2 diabetes. The so-called "obesity paradox" has caused some confusion. Two meta-analyses have shown that overweight or obese patients with type 2 diabetes have a lower cardiovascular mortality than their normal-weight counterparts. Otherwise, studies on possible relationships between body mass index (BMI) and diabetes sequelae have yielded ambiguous and sometimes contradictory results.
Elli Polimeti and her colleagues from the German Institute of Human Nutrition (Deutschen Institut für Ernährungsforschung or DIfE) in Potsdam-Rehbrücke have now investigated how BMI before diabetes diagnosis and the further development of body weight affect the risk of diabetes-associated micro- and macroangiopathies. To do this, they use data from the EPIC Potsdam cohort, which included 27,548 adults from Germany. The initial examination of the participants took place between 1994 and 1998 and included BMI among many other parameters. By 2009, 1,601 participants in the EPIC Potsdam cohort had been diagnosed with type 2 diabetes. The analysis was limited to those who did not have any late complications at the time of diabetes diagnosis (n=1,081).
During the observation period of 10.8 years on average, 85 macrovascular complications (strokes and heart attacks) and 347 microvascular events such as nephropathy, neuropathy and retinopathy occurred in these patients.
A higher BMI before diabetes diagnosis was associated with a significantly higher rate of late microvascular complications. There was a clear dose dependence, i.e. the fatter the patients, the higher the risk (per BMI increase of 5 kg/m2 plus 21%). This association was clearest for nephropathy (+39% per BMI increase of 5 kg/m2), followed by neuropathy (+12% per BMI increase of 5 kg/m2). The association was independent of factors such as dyslipidaemia and hypertension, and gender, age and smoking status had no influence. In contrast, a statistically significant association of BMI before diabetes diagnosis with macrovascular complications could not be found (HR per BMI increase by 5 kg/m2 1.05).
The research team also examined the influence of weight changes in the time after the diabetes diagnosis. Here, too, there was a clear connection with microvascular complications: if the patients succeeded in losing weight, the risk of nephropathy and neuropathy was also reduced. Further weight gain, on the other hand, also increased the risk of developing such complications. In contrast, the risk of macrovascular complications was not influenced by weight development.
In conclusion, the study once again underlines how important it is to fight overweight and obesity. In particular, the risk of microvascular diabetes sequelae could be significantly reduced by weight loss even before diabetes develops.
Source:
Elli Polimeti et al; BMI and BMI change following incident type 2 diabetes and risk of microvascular and macrovascular complications: the EPIC-Potsdam study; Diabetologia (2021); 64: 814-825.