Despite the introduction of novel treatment strategies, diabetic microvascular complications remain a major cause of morbidity and mortality in individuals with diabetes. Though many traditional risk factors have been identified in individuals with older onset diabetes, the relationship between different diabetic microvascular complications in youth onset diabetes has not been clearly described.
The aim of the present study was to determine whether the presence of one microvascular complication (diabetic retinopathy, diabetic nephropathy, or diabetic neuropathy) would predict the risk for the development of another microvascular complication among individuals with youth onset, type 1 and type 2 diabetes
The study was conducted among a sub population of individuals with youth onset type 1 and type 2 diabetes, enrolled under the Indian Council of Medical Research - Registry of people with diabetes in India with young age at the onset (ICMR - YDR) from the Chennai and New Delhi centres. We obtained prospective data of 799 type 1 and 371 youth onset type 2 diabetes individuals from the registry database (baseline data of these individuals were collected between 1stJanuary 2001 and 31st December 2012 and their follow up data collected till 31st December 2014 were used for analysis). For assessing diabetic retinopathy, a dilated fundus examination with direct ophthalmoscope, by an experienced ophthalmologist, was done. Diabetic nephropathy was diagnosed, if 24 hour urine protein excretion was greater than 500mg or urine albumin excretion was greater than 300mg. Diabetic neuropathy status was assessed by clinical examination and the monofilament test. Demographic and clinical characteristics of the study population were assessed using standardized baseline and follow up proformae. The anthropometric and biochemical tests were measured using standard methods. Separate multivariable cox regression models were used to evaluate the relationship between the microvascular complications in type 1 and type 2 diabetes, after adjusting for age, gender, duration of diabetes, hypertension, obesity and glycemic control. Any microvascular complication was defined as the presence of nephropathy and neuropathy in the case of retinopathy and likewise for the other two complications.
In type 1 diabetes, the presence of any microvascular complication at baseline was an independent predictor of incident diabetic retinopathy [adjusted hazard ratio (95% C.I) - 2.5 (1.1, 6.3)] and nephropathy [adjusted hazard ratio (95% C.I) -4.1 (1.5, 11.9)]. In youth onset type 2 diabetes, those who had a history of any microvascular complication at baseline, were at 3.8 times higher risk of developing diabetic neuropathy at follow up [adjusted hazard ratio (95% C.I) - 3.8 (1.8, 8.2)] and 3.3 times higher risk of developing nephropathy [adjusted hazard ratio (95% C.I) - 3.3 (1.2, 9.1)]. These were independent of other covariates such as duration of diabetes and hypertension.
Our data suggests that the presence of a pre-existing microvascular complication is associated with the development of another in individuals with both youth onset type 1 and type 2 diabetes. Additional research on the timing and progression rate of the diabetes related complications, relative to one another, is required to further refine the risks posed to each individual. The findings of current study, emphasize the need for screening for other microvascular complications when an individual with youth onset diabetes has been diagnosed with one complication. Such individuals should also be managed aggressively to prevent or delay the onset of other complications.