We report a case of a 9-year-old Nigerian boy with confirmed type1diabetes (T1D) and whose three elder siblings (sisters) had pre-diabetes, defined by impaired fasting blood glucose, using the ISPAD most recent criteria. The fasting blood glucose levels of the siblings of the index patient were 6.1mmol/L, 5.9mmol/L and 5.6mmol/L, respectively. On insulin therapy, the boy‘s diabetes was well controlled with no hypoglycaemic episodes. The father of the index patient has type 2 diabetes mellitus and his diabetes was initially controlled with oral glucose-lowering agent for 10 years before switching to insulin therapy in the last seven years, following poor glycaemic control with the initial therapy. The three siblings of the index patient are currently being followed up with periodic retesting, using fasting and/or 2-hour postprandial blood glucose determinations as suggested in ISPAD recent guideline. Conclusion: A high index of clinical suspicion of diabetes mellitus is required in the siblings of any child with type 1 diabetes
