INS and morbid obesity: In multivariable regression analysis, including HbA1c, age, sex, ethnicity, education level, income, smoking, hypertension, dyslipidaemia, renal and neurological disease, morbid obesity, and insulin use as covariates, Gange 2021 found that peripheral circulatory disorders were associated with development of PDR (OR 1.88, 95% CI 1.25 to 2.83; P = 0.003) whereas diabetic ketoacidosis was not (OR not reported, P > 0.05) (Gange 2021).