Type 1 Diabetes Problems Greater With Family History of Type 2 Diabetes

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Type 1 and type 2 diabetes both increase the risk of diabetic-related complications. Researchers examined whether a family history of type 2 diabetes increased the risk of complications in people with type 1 diabetes.

People with type 1 diabetes (T1D) who have first-degree relatives with type 2 diabetes (T2D) may be at increased risk for diabetes-related complications, according to results of a Taiwan-based study published in JAMA Network Open.

Data for the population-based cohort study were sourced from the Taiwan National Health Insurance Research Database (NHIRD). Between 1995 and 2017, 21,767,880 parent-child relationships, 16,245,232 full sibling pairs, and 260,844 twin pairs were assessed. Of these groups, 11,237 people had been diagnosed with T1D.

Patients in the database diagnosed with T1D were aged mean 22.7 years (standard deviation [SD], 14.4), and 54% were women.  

Those with T1D who had a first-degree relative with T2D has an increased risk for diabetic nephropathy (adjusted hazard ratio [aHR], 1.44; 95% CI, 1.27-1.64; P =.01), hyperlipidemia (aHR, 1.36; 95% CI, 1.21-1.51; P <.001), retinopathy (aHR, 1.28; 95% CI, 1.12-1.47; P =.02), and peripheral neuropathy (aHR, 1.24; 95% CI, 1.06-1.47; P <.001).   The risk for major adverse cardiovascular events (MACE) was also higher (aHR, 2.61; 95% CI, 1.32-5.16) at an age of diagnosis of less than 20 years.

Stratified by gender, men with a family history of T2D had an increased risk for nephropathy (aHR, 1.51; 95% CI, 1.24-1.83; P <.05), hypertension (aHR, 1.38; 95% CI, 1.13-1.69; P <.05), and hyperlipidemia (aHR, 1.32; 95% CI, 1.11-1.57; P <.05). In women, there was an increased risk for retinopathy (aHR, 1.40; 95% CI, 1.17-1.66; P <.05), nephropathy (aHR, 1.37; 95% CI, 1.16-1.63; P <.05), hyperlipidemia (aHR, 1.37; 95% CI, 1.19-1.58; P <.05), and peripheral neuropathy (aHR, 1.25; 95% CI, 1.01-1.56; P <.05).

The researchers acknowledged several study limitations, including the relatively small incidence of T1D in Taiwan and a lack of data regarding glycemic control from the database reviewed.

“Having type 1 diabetes as well as a family history of type 2 diabetes was associated with increases in individual risks of hypertension, hyperlipidemia, microvascular complications, and MACEs,” the study authors concluded. “An increased focus on this patient population in the prevention of these diabetes complications is warranted in further clinical investigations.”


Lin C-H, Lo F-S, Huang Y-Y, et al. Evaluation of disease complications among adults with type 1 diabetes and a family history of type 2 diabetes in Taiwan.  JAMA Netw Open. 2021;4(12):e2138775. doi:10.1001/jamanetworkopen.2021.38775