Screening of Undiagnosed Hypothyroidism in Elderly Persons with Diabetes according to Age-Specific Reference Intervals for Serum Thyroid Stimulating Hormone and the Impact of Antidiabetes Drugs

Table 4

Prevalence of hypothyroidism, TSH, and FT4 in subgroups of hypothyroid patients with diabetes.

	Subgroups of antidiabetes drugs				values
	MTF	SU/DPP4/TZD	INS	MTF+
Hypothyroidism (%/)	4.5% (10/224)	6.5% (14/215)	7.5% (4/53)	6.6% (17/259)	MTF × other groups < 0.05; MTF+ × other groups NS
TSH (mU/L)
Median	11.8	15.0	17.5	13.5	MTF × other groups < 0.05; INS × other groups < 0.05; MTF+ × other groups NS
25–75%	11.6–14.2	11.2–17.1	13.2–19.3	11.7–15.6
95% CI	11.5–13.7	14.5–15.5	17.0–18.0	12.9–15.9
FT4 (pmol/L)
Mean	11.7	11.1	9.8	10.9	NS
SD	±0.5	±0.5	±1.3	±1.3
95% CI	10.3–15.4	10.3–15.4	9.0–11.6	9.0–11.6

TSH: thyroid stimulating hormone; FT4: free thyroxine; 25–75%: 25–75 percentiles CI: confidence interval; NS: not significant. MTF: metformin; SU/DPP4/TZD: sulfonylureas, dipeptidyl peptidase 4 (DPP4) inhibitors, and thiazolidinedione analyzed together. For converting FT4 in nd/dL, multiply pmol/L by 0.078.