Background Poor access to affordable insulin results in serious and needless complications and premature deaths for those with diabetes who need this essential medicine. To help address this issue, we assessed insulin availability, prices, affordability and price components in Hubei Province as China has the heaviest burden of diabetes globally. Methods In 2016, insulin availability and price data was collected in the capital and five other cities. A total of 30 public sector outlets (hospitals and primary care institutions) and 30 private pharmacies were sampled, using an adaptation of the World Health Organization/Health Action International methodology, Data was collected for all human and analogue insulins in stock, then analyzed by type (prandial, basal or pre-mixed) and duration of action. Prices were expressed as Median Price Ratios (MPRs) to Australian PBS prices. Price components were tracked for five insulin products in two cities.. Affordability was assessed as the number of days’ wages of the lowest paid unskilled government worker needed to purchase 10 ml 100 IU/ml (approximately 30 days’ supply). Results Mean availability was highest in public hospitals for prandial (70%), basal (80%) and pre-mixed insulin (90%). In primary care institutions and private pharmacies mean availability ranged from 10% to 33%. Median prices of all insulin types were higher that Australian PBS prices in all three sectors for human and analogue insulins (ranging from1.36–2.59 times). Patients have to pay 4 to 16 days’ wages to purchase a month’s treatment depending on the insulin type and sector. The largest component of the patient price was the manufacturers’ selling price (60%). Taxes in the form of import duties and VAT are applied in some sectors. Conclusions The availability of insulin in primary care institutions and private retail pharmacies was very low in Hubei. Only public hospitals had good insulin availability. Insulin prices were high in all sectors making this life-saving medicine unaffordable, especially for those on low incomes. Governments should consider using its bargaining power to reduce prices, abolish taxes on essential medicines such as insulin, and develop strategies for more equitable access to insulin. Electronic supplementary material The online version of this article (doi:10.1186/s12913-017-2553-0) contains supplementary material, which is available to authorized users.