Respiratory Effects of Insulin Sensitisation with Metformin: A Prospective Observational Study

Figures & data

Figure 1.  Flow chart depicting participant recruitment and study design.

Table 1.  Baseline characteristics of study participants

	Median (range)
n	17
Male (%)	65
Age (years)	61 (42–74)
Height (cm)	173 (153–187)
Weight (kg)	89.4 (69.6–153.8)
BMI (kg/m^2)	29.1 (25.2–55.1)
Pack years (smokers only)	30 (14–114)
Diagnosis of asthma (%)	47
eGFR (mL/min)	83 (58–117)
Impaired fasting glucose (%)	88
Impaired glucose tolerance (%)	12
Type 2 diabetes mellitus (%)	13
HbA1c, mmol/mol	42 (37–61)
FEV1 (% predicted)	63 (33–78)
FVC (% predicted)	88 (50–114)
FEV1/FVC ratio	0.53 (0.26–0.73)
FEV1/FVC ratio (% predicted)	69 (34–92)
GOLD stage II	65
GOLD stage III	35
DLCO (L)	21.0 (10.7–38.1)
DLCO (% predicted)	84 (52–137)
Baseline dyspnoea index (BDI)	7 (3–10)

Figure 2.  Change in St George's Respiratory Questionnaire total score. The dashed line shows change in the median score.

Table 2.  Changes in health status and symptoms

Variable	Baseline Median (range)	Week 26 Median (range)	Change Median (range)	p value
SGRQ score (total)	45 (11–72)	39 (3–66)	−5 (−29–6)	0.0051
SGRQ score (symptoms)	65 (6–100)	50 (6–84)	−11 (−59–22)	0.0936
SGRQ score (activity)	54 (18–86)	48 (0–85)	−1 (−54–15)	NS
SGRQ score (impacts)	32 (0–77)	28 (0–58)	−4 (−32–4)	0.0042
Transitional dyspnoea index (total)	–	2 (−3–5)	–	0.0114
Transitional dyspnoea index (functional impairment)	–	0 (0–1)	–	0.0369
Transitional dyspnoea index (magnitude of task)	–	1 (−2–2)	–	0.0283
Transitional dyspnoea index (magnitude of effort)	–	1 (−1–2)	–	0.0120
Shuttle walk distance (m)	250 (90–530)	340 (130–630)	15 (−70–150)	0.1137
Borg score at test end	4 (1–7)	3 (1–7)	−1 (-4–2)	0.0441

Table 3.  Changes in lung function, gas transfer and exhaled nitric oxide

Variable	Baseline Median (range)	Week 26 Median (range)	Change Median (range)	p value
FEV1 (L)	1.54 (0.87–3.02)	1.66 (0.83–3.41)	0.03 (−0.34–0.65)	NS
FEV1 (% predicted)	63 (33–78)	63 (29–81)	1 (−9–19)	NS
FVC (L)	3.43 (2.02–5.58)	3.48 (2.16–5.36)	0.07 (−0.65–0.89)	NS
FVC (% predicted)	88 (50–114)	92 (59–107)	2 (−12–20)	NS
FEV1/FVC ratio	0.53 (0.26–0.73)	0.56 (0.27–0.67)	0.01 (−0.11–0.10)	NS
FEV1/FVC ratio (% predicted)	69 (34–92)	73 (35–89)	1 (−15–12)	NS
TLC (L)	6.53 (4.31–9.94)	6.35 (4.16–9.84)	−0.16 (−0.57–0.42)	0.0995
TLC (% predicted)	105 (85–136)	101 (80–138)	−3 (−8–9)	0.1475
RV (L)	3.24 (1.77–4.42)	2.87 (1.49–4.30)	−0.28 (−0.91–0.52)	0.1208
RV (% predicted)	136 (89–171)	123 (60–170)	−13 (−36–28)	0.0833
RV/TLC ratio	0.44 (0.35–0.67)	0.45 (0.27–0.55)	−0.03 (−0.13–0.07)	0.1167
RV/TLC ratio (% predicted)	115 (88–159)	111 (65–146)	−6 (−30–18)	0.1297
FRC (L)	3.85 (2.36–5.60)	3.32 (2.20–5.82)	−0.09 (−0.72–0.34)	NS
FRC (% predicted)	116 (83–161)	109 (85–170)	−2 (−19–9)	NS
VC (L)	3.50 (2.17–5.61)	3.51 (2.16–5.54)	0.04 (−0.46–0.69)	NS
DLCO (L)	21.0 (10.7–38.1)	19.0 (10.1–34.5)	−0.6 (−5.5–2.7)	0.0883
DLCO (% predicted)	84 (52–137)	80 (49–140)	−3 (−22–13)	0.0736
ENO (ppb)	34 (8–220)	28 (10–135)	−4 (−85–52)	NS

Table 4.  Changes in general and respiratory muscle strength

Variable	Baseline Median (range)	Week 26Median (range)	ChangeMedian (range)	p value
PImax (cmH2O)	68 (26–157)	76 (53–165)	7.5 (−8.0–50.0)	0.0090
PImax (% predicted)	74 (36–135)	82 (51–142)	7 (−10–66)	0.0130
PEmax (cmH2O)	94 (54–173)	108 (58–235)	3 (−31–48)	NS
PEmax (% predicted)	56 (33–89)	59 (34–106)	1 (−16–35)	NS
Mean grip strength, dominant hand (kg)	31 (20–59)	30 (17–61)	−1.4 (−9.5–2.2)	0.0448
Mean grip strength, dominant hand (% predicted)	83 (64–122)	77 (58–120)	−2.8 (−30.6–5.4)	0.0395
Maximum grip strength, dominant hand (kg)	33 (20–62)	32 (19–62)	−1.2 (−10.3–3.5)	0.0244

Figure 3.  Changes in inspiratory mouth pressures (PI_max). The dashed line shows change in median PI_max.