Smoking and Diabetes Control in Adults With Type 1 and Type 2 Diabetes: A Nationwide Study From the 2018 National Program for Prevention and Control of Diabetes of Iran

Objectives: Smoking is among the top leading causes of morbidity and mortality worldwide. To date, studies on the association between smoking and diabetes complications and metabolic control have shown conflicting results. In this study, we aimed to assess the association of smoking with micro- and macrovascular complications of diabetes and lipid and glycemic indices. Methods: We used the National Program for Prevention and Control of Diabetes of Iran database of 99,651 adult patients with diabetes across Iran. Multiple logistic regression models were used to examine the association between smoking and diabetes complications including cardiovascular disease, neuropathy, nephropathy and retinopathy. This association was adjusted for age, sex, duration of diabetes, glycated hemoglobin (A1C), hypertension, hyperlipidemia, medication, obesity and type of diabetes. Results: Smoking was associated with cardiovascular disease, nephropathy, retinopathy and neuropathy (odds ratios [ORs1 for patients with type 1 diabetes were 1.51, 2.29, 2.70 and 2.40, respectively; for patients with type 2 diabetes, ORs were 1.27, 1.21, 1.51 and 1.70, respectively; all with p values <0.001). Among patients with type 1 diabetes, smoking was significantly (p<0.05) associated with A1C (OR, 2.12), 2-h postglucose level (OR, 1.30), triglycerides (OR, 1.48) and high-density lipoprotein (HDL) control (OR, 1.34). Among patients with type 2 diabetes, smoking was significantly associated with A1C (OR, 1.09) and HDL control (OR, 1.21). Conclusions: Smoking was associated with multiple diabetes complications including cardiovascular disease, neuropathy, nephropathy and retinopathy and worse A1C and HDL control in both patients with type 1 and type 2 diabetes. It was also associated with worse 2-h postglucose level and triglyceride control among patients with type 1 diabetes. Our findings signify that national programs for smoking prevention and cessation may be beneficial to diabetes control in Iran. (C) 2019 Canadian Diabetes Association.