As per current evidence, individuals with hypothyroidism and lower free thyroxine (FT4) levels in the reference range have an elevated risk of type 2 diabetes. There is a need for further population-based studies to address this association given the limited evidence.

• From Embase, Medline (Ovid), Web of Science, Cochrane, and Google Scholar, prospective studies examining the link of thyroid function and incident type 2 diabetes were identified.

• Researchers found 4574 publications of which 7 met the inclusion criteria and were included in the qualitative synthesis and six publications were analyzed in the meta-analysis.

• Pooled hazard ratios for the risk of type 2 diabetes were 1.26, 1.16, 1.06, and 0.95 for hypothyroidism, hyperthyroidism, thyrotropin in the reference range, and for FT4 in the reference range, respectively.